Fix Your Own Car (Best Mechanics Tips... Ever!)

I’m a mechanic for about twenty years and the one question I am asked a ton is “How many car repairs can owners do themselves? The answer is quite a lot actually.

To fix your own car safely and successfully you’ll need safety equipment, basic hand tools, and a little auto maintenance knowledge. Routine car maintenance that may be safely undertaken by owners include:

Change oil and oil filter
Replace spark plugs
Replace air filter
Check transmission
Check coolant system
Check drive belt
Scan ECM for faults
Check Brake systems
Check steering
Check suspension
Check drive-line
Check tire condition
Check tire pressures
Rotate wheels
Check battery health
Check alternator
Clean battery terminals
Replace cabin filter
Check A/C system
Replace bulbs
Replace fuses
Replace wiper blades
Fill Windshield washer
Lube door locks and hinges
Lube window rubbers
Paint work repairs

In this post you’ll learn about the routine car maintenance items you can do yourself, I’ll also share my professional tips on completing them successfully and safely.

You’ll learn about the type of maintenance and repairs that are best left to the professionals, and I’ll tell you why.

Lots of owners think car maintenance and repair are complex. While it’s true to say some areas of the automobile are quite technical. Most routine repairs are just plain common sense and can easily be tackled with just some basic tools, hand skills, and minimal mechanical knowledge.

Is It Legal To Work On Your Car?

It’s worth noting, that while most states allow the homeowner to take care of routine car maintenance on their property, some states won’t allow any car maintenance that requires special tools. Best to check your state’s laws before commencing work in your driveway.

Automotive Systems Categories

Autos have become more complex in certain areas over the last twenty years. The addition of computers has made some tasks such as fault-finding a lot easier and at the same time, in some cases a lot harder.

Most cars made in the last twenty years will employ a computer to manage engine operation. Latest gen cars use a ton of computers, each system has its own computer. For example, engine, transmission, ABS system, Airbag system, HVAC, infotainment system, etc all have their own dedicated computer to help manage their range of functions.

Different manufacturers use different names for these computers, so don’t be put off by complex-sounding acronyms. They’re all referring to the same thing.

The engine module is commonly known as the PCM (Power-train control module) but other manufacturers may call them by other names such as ECM (Engine Control Module) or ECU (Engine Control Unit).

As autos became more sophisticated, and in an effort to organize all these new systems logically, manufacturers usually group them into four main categories, they are:

Power-train
Chassis
Electrical
Body and trim.

1 Power-train

The power train covers the engine including all its components, Fuel system, Exhaust system, and Transmission.

2 Chassis

Chassis covers Suspension, Drive-line, Brake system, and Steering system.

3 Electrical

Covers all the major and minor electrical components and systems such as Battery, Alternator, Instrument panel, HVAC, etc, all the way down to the car horn.

4 Body & Trim

Body & Trim covers all the bodywork and coachwork but also wipers, door locks, and windows, sunroof, trunk closures, etc.

DIY Car Maintenance

Professional shops will charge in excess of $100 an hour labor, so makes sense to do as much of the easy work yourself. But what type of car maintenance can undertake by the owner? Under each of the four main categories, I’ve listed regular maintenance work that you could easily do at home in the driveway without specialized tools.

At the end of each category, I’ll include a list of common component failures and their fault symptoms. I’ll also advise if the owner could realistically fix these types of repairs too, or if it’s better suited to a professional.

Power-train Maintenance

The Power-train category requires the most amount of maintenance and repair. And since it’s the business end of a car and covers a ton of components, it’s not surprising. In this category, we’ll list the maintenance jobs you can easily take care of.

Change Oil & Oil Filter

Changing the engine oil and filter is top of the list because it’s super important and also one of the most common power-train maintenance tasks. It’s not difficult but a few simple tips will help you nail it the first time out.

Oil is traditionally drained from the engine by lifting the car on a hoist and removing the oil drain bung, when removed the oil simply drains out. It’s common practice to replace the oil drain bung or crush washer to prevent oil weeping from the bung after installation.

Instead, as you’ll be working from the driveway, use an oil siphon to suck the oil from the engine pan through the dipstick tube.

Sure, draining is a better job, but the siphon eliminates all the mess and fuss with jacking and removing covers, and dropping the car to drain and spilling…..

pro tips:

Before draining, warm the engine.
Check you have the correct oil and filter.
Check you have a suitable oil filter removal tool.
When fitting the oil filter, lube the filter seal with engine oil.
Tighten the oil filter only hand tight.
After starting and idling the engine, recheck and top up to the full mark.

Replace Spark Plugs

Spark plugs are important to your engine economy a bad plug will cause misfiring which if ignored can cause some more expensive problems like damaged Catalytic Converters.

Many cars use long-life spark plugs, and that can be good or bad, good if you have a lot less than one hundred thousand miles on the clock, as the plugs need to be changed at 100k. Long-life plugs are more expensive than the regular type plug, usually about $10 each.

pro tips:

Remove the plugs when engine cold.
Use a deep reach socket, know as a plug socket, extension and ratchet to remove the plugs.
Visually check plug electrode gaps before fitting.
When fitting the new plugs don’t allow the plug to fall down the plug shaft, this could close the electrode gap and cause an engine misfire.
Start threading the new plugs by hand never with the ratchet.
When the new plug is snug by hand, tighten a further quarter to half turn, or if you have a torque wrench tighten 14mm to 30Nm and 18mm to 40Nm.

Replace Air Filter

A clean and clear airway is important especially to turbo-charged engines. It filters the air from silica which prevents internal engine erosion, without the filter fine-grit would sandblast the internals.

But the filter also settles the air into a uniform stream which helps the MAF sensor produce timely and accurate air quantity readings to the ECU.

Removing the filter is usually the easiest job under the hood, many air boxes are tool less fit.

pro tips:

Clean the air filter housing before fitting a new filter.
Spray contact cleaner on the MAF (Mass Air Flow) sensor before closing the air box.

Check Transmission

Transmission oil should be checked when the engine is warm and idling. A transmission oil change is usually performed every thirty thousand miles or more often if heavy towing. Some late model cars don’t recommend changing the oil at all. I’ll watch that one with great interest.

Depending on the engine layout, transmission filters are normally changed on rear-drive transmissions along with a new pan gasket.

Transverse (Front-wheel-drive) auto transmission filters are often not serviceable.

pro tip:

Use recommended transmission oil only, as transmissions are very sensitive to viscosity (flow rates).
Performing a transmission flush or even changing the transmission oil on a high mileage transmission can cause more problems than they solve.

Check Coolant System

The coolant system is what stops your engine from overheating and blowing a head gasket, or worse seizing. The coolant itself is specially formulated to keep the system cool when stressed and also to prevent it from freezing in colder conditions.

The coolant also contains anti-corrosion properties and a lubricant. Both these qualities help maintain system components such as hoses, gaskets, pumps, rad, heater core, thermostat, and engine metal in tip-top condition.

Old coolant not only doesn’t offer engine protection, but it’s also actually harmful as it turns acidic which eats at the engine and coolant system components.

An inexpensive coolant tester is useful or just go ahead and change it if it’s older than three years. Fresh coolant will offer protection at 226°F and down to -29°F.

You can change the coolant yourself, but be sure to purge the sir from the system, trapped air can cause engine damage.

pro tip:

Back flush coolant system every 3 years.
Change coolant every 3 years.
Change thermostat every 3 years.
Top up coolant system between services with coolant not water.

Check Drive Belt

Check and change the Auxiliary belt aka serpentine, fan, or drive belt. They work super hard as they take drive from the crankshaft pulley and power the alternator, power steering, air-conditioning pump, and sometimes the water pump too.

If your water pump is driven by the aux belt (most are not), and it breaks, your engine will overheat. Expect to change it every fifty thousand miles.

pro tip:

Cracking, squealing sound or a glazed appearance means it’s time to change the belt.
Better to change before it breaks.

Scan ECM For Faults

Modern cars as you know are run by control modules (Computers) and one of the greatest advantages of modern cars is their ability to self-diagnose. When a systems computer sees a fault it stores a unique fault code, if the problem is serious it will illuminate a warning such as an engine light or an ABS light etc.

A simple scan tool can be super useful for reading your car’s engine trouble codes. Your engine may not display an engine light but could still have fault codes logged. Reading and clearing them at a tune-up is good practice as it allows you to monitor the vehicle’s health.

Some very clever plug-in readers allow you to read codes from an app on your smartphone which will also update and alert you to any live manufacturer recalls due on your vehicle.

pro tip:

Record all trouble codes before clearing them.
Check on-line data base for know problems or recalls.

Power-train Common Problems

Here we’ll look at the most common problems associated with the power train, we’ll list their symptoms, and also if the novice mechanic could realistically undertake the repair.

Fuel Pump Fault

What does it do? The fuel pump as its name suggests feeds the engine with gas.

Failure symptoms include No start or poor performance; P0230 code may be logged.

Can I fix this? The pump lives inside the fuel tank and often the rear passenger seat floor area will have a service access cap, in other cases, the fuel tank will need to be dropped. If your vehicle has service access then replacement by the novice is possible, but it’s at the top end of the skill level.

Coil Failure

What does it do? The Coil produces the high voltage required to fire the spark plug.

Failure symptoms include Misfiring, rough running & idling engine; Poor performance and fuel economy; Engine light; Code P0351.

The coils are under a ton of stress and are a frequent failure. There are a few different types, a coil per cylinder or a coil pack. The coil per cylinder often called COP (Coil Over Plug) or pencil coil are the least expensive.

Can I fix this? Yes, this is a pretty easy fix, it’s a plug-and-play type repair.

Crank Shaft Sensor Failure

What does it do? The crank sensor (CKP) is positioned at the crankshaft and produces a signal which the ECU uses to initiate the engine start procedure and when running to adjust timing and fire the plugs at the correct time.

Failure symptoms include: In most cases, it’s a crank with no start; Engine stalls when hot is also common; Fault code P0335.

Can I fix it? Most are a plug-and-play type deal and others will be a little more work (remove Harmonic balancer) and others again will be a lot more work (remove transmission).

Fuel Injector Failure

What does it do? Injects gas directly into the intake manifold.

Failure symptoms include Misfiring engine; Engine light on; Black smoke; P0200 fault code or similar set.

Can I fix it? Replacing an injector is usually pretty straightforward, however, some engines may require the removal of the intake plenum and that may require replacement gaskets.

MAF Failure

What does it do? The MAF (Mass Airflow Sensor) measures the quantity of air entering the engine. The ECU needs this information in order to add the correct amount of gas to the engine.

Failure symptoms include Poor running; No power; Hard starting; Code P0101.

Can I fix it? Replacing the MAF sensor is pretty easy, it’s plug-and-play.

EGR Failure

What does it do? The EGR (Exhaust Gas Re-circulation) is an electro-mechanical valve that directs spent exhaust gases back to the combustion chamber where they reduce temperatures which in turn reduces harmful NOx emissions.

Failure symptoms include: Stalling at idle; Rough running; No power; Engine light on; Code P0401.

Can I fix it? Some EGR valves are easy to access and some are a total pain in the jacksie. If it’s berried down the back of the engine you’ll need a ton of patients and a good selection of tools.

EVAP Failure

What does it do? The Evaporator system is a sealed system that captures gas tank fuel vapors and rather than vents them to the atmosphere, the system feeds them back into the combustion chamber in a controlled manner.

The system contains the following components: Vent solenoid; Canister; Sealed gas tank; Tank pressure sensor; Gas cap; Purge solenoid; Pipework.

Failure symptoms include Engine light on; Rough idle; Hard starting; Codes P0440.

Can I fix it? In lots of cases the EVAP code was set by a loose gas cap, simply tightening the gas cap fixes the problem. Worn seals on the gas caps causing a tank pressure leak are also a common cause of EVAP faults.

CMP Fault

What does it do? The CMP (Camshaft Position Sensor) is fitted to the camshaft and monitors cam position. The ECU monitors cam relative to the crankshaft, to adjust timing fuelling.

Fault symptoms include: Rough idle; Stalling; No starts; Code P0340 set.

CMP error codes are often triggered when cam and crank are out of alignment by a few degrees. This is usually caused by stretched timing chains and replacing the CMP won’t fix the problem.

Can I fix it? Replacing the CMP sensor is easy, it lives at the top of the engine and is usually easily accessible.

O2 Sensors

What does it do? The oxygen sensors measure oxygen inside the exhaust, which the ECU uses, these readings to adjust fuel when the vehicle is in a closed-loop.

Failure symptoms include: Misfiring engine; check engine light on; Poor performance; Code such as P0141- 0142 – 0143 – 0144. The code will indicate the bank, upstream or downstream, sensor type fault.

Can I fix it? While it is possible for the novice to replace the O2 sensor, they are known for their stubbornness and a special sensor removal socket may be needed.

Catalytic Converter Faulty

What does it do? The catalyst is fitted to the exhaust system and captures hydrocarbons. As the engine operates the catalyst heats up and burns off the unburnt fuel.

Failure symptoms include Rotten egg smell; Rattling sound from the exhaust; Poor engine performance; Engine light on; Code P0420.

Can I fix it? Replacing the catalyst is a job for a workshop hoist, and possibly some cutting and heating tools may be needed.

Turbo Faults

Turbo chargers are fitted to lots of cars today, they don’t just make them more powerful they also make them more efficient. Turbos are durable, but they won’t tolerate low or poor oil quality. Turbo pipes, solenoids issues, over-boosting, and wastegate issues are among the common less serious turbo problems.

I wrote a post about turbo diagnostics here “Car won’t build boost”.

Chassis Maintenance

The Chassis category covers brakes, steering, suspension, and drive system. The brake system sub-category tends to require the most maintenance. City cars do more start-stop work so if yours is a city car, you’ll be getting to know your brake system very well indeed.

Check Brake Systems

In a world that’s increasingly turning electric, auto brakes thankfully are still mechanical and hydraulic. Most use rotors and floating brake calipers all around, with parallel electronic ABS. Parking brakes are mostly still cable but electric motors are becoming common.

Common wearing components are pads and rotors. When rotors become thin, they warp easily. Pads wear at different rates depending upon the driving environment and style.

Pads may be checked without taking the wheel off, as most cars run alloy spoke wheels which offer a great view of both the pads and the rotor.

When worn the rotor develops a groove top and bottom of the friction area, the spec is usually about 1 mm. If you can catch your nail on the groove, it’s likely you need a set of rotors or resurfacing.

Brake lines, flexi hoses, calipers, master cylinders need to be checked for corrosion, cracks, and leaks.

The brake booster can be checked by applying the foot brake and starting the engine, a healthy booster will allow the pedal to sink a little further, and stop.

The brake fluid should be changed every 3 years as it attracts moisture which can attack the brake system components.

The handbrake should be checked and adjusted if necessary.

pro tip:

Remove brake fluid cap before retracting caliper pistons.
Rear caliper pistons, won’t push back instead they must be screwed and pushed. It’s also not uncommon for a left hand rear caliper to screw back anticlockwise and the right had rear, clockwise.
When fitting brake pads, apply some dry grease such as Moly or graphite or some copper grease to the pad shoulders and rear.
Never use petroleum grease near rubber components such as floating caliper pin boots,instead use silicone grease.
Ignition on, ABS light should illuminate for a few seconds and then turn off, this is the ABS system self diagnosing. If it detects a problem the light stays on.

Check Steering

The steering on most autos is rack and pinion with hydraulic power assistance. Electrically assisted steering is also becoming common and is much less maintenance.

The racks themselves aren’t serviceable, outer ball joints are replaceable, known as tie rods inner, and inner assembly is also replaceable so too are the steering bellows.

Check hydraulic steering pumps and hoses for noise and leaks. The fluid should be replaced every 3 years.

pro tip:

Jack up the wheel and using your hands at the three o’clock position, rock the wheel and feel for movement.
Steering alignment will be needed if steering ball-joints are replaced.

Check Suspension

McPherson struts front and trailing arms rear is a pretty common suspension set-up. Higher-end cars may opt for a double a-arm fully independent set-up which is not surprisingly more expensive to repair.

Check struts for leaks, compressing each corner of the vehicle to gauge operation. While test driving, lurching or diving on corners or while braking indicates weak shocks.

Check for broken springs, a car that sits lower in one corner is a sure sign spring has broken.

Check upper and lower A-arm ball joints. A ball joint is also employed to connect the McPherson strut to the knuckle. The ball joints suffer from excessive free-play, they may also cause a knocking noise over rough ground.

Drop links and anti-sway bar bushings are also common to wear items. Rear trailing arm bushings are prone to wear on some vehicles.

pro tip:

Use a pry bar to check for movement at the ball-joint.
Jack up the wheel and using your hands at the six o’clock position, rock the wheel and feel for movement.

Check Drive-line

Your car may be from the rear or four-wheel drive. Front-drive vehicles have the engine fitted transversely which means the driveshafts are 1/2 shafts. The outer CV (Constant Volatility) joints are prone to torn boot tears and noisy joints.

Check for a torn boot. They will need to be addressed as road grit and water enters and the grease leaves the joint which will shorten its life. Inner 1/2 shafts joints rarely give much trouble today.

Rear-drive vehicles will employ a driveshaft from the transmission to the rear differential. Most employ a U-joint or two and are prone to wear. A carrier bearing is also used to align and support the drive.

pro tip:

Some U-joints are fitted with grease nipples and will always benefit from a shot of grease.
Check and top up if necessary rear differential, from drive cars differentials are lubed by the transmission.

Check Tire Condition

Tire condition is really important, we rely on four small contact patches of rubber for our safety. The tire needs to be evenly worn, a tire that’s worn on the inside suggests the vehicle is towed in and needs alignment.

Tires are worn on the outside, it’s towed out and needs alignment. Worn on the shoulders, means the tire is underinflated, and worn in the center means it’s overinflated. Check also for tears or nails.

A vehicle will ideally have matching make and model tires all around or at least match them to the same axle. Using different size tires is dangerous and could damage the vehicle’s transmission or differential.

Check the date and DOT stamp on your tires, riding around on old rubber is dangerous. Old is more than five years.

Check Tire Pressures

Tire pressures should be as per manufacturers spec. You’ll find a useful label usually inside the driver’s door pillar, inside the gas flap, or in the user’s manual.

Rotate Wheels

When I was an apprentice rotating the wheels was a big deal, customers came back just for a rotation. Now it’s not really a thing. Besides, cars with directional tires can’t rotate, the tire would run the wrong way.

Chassis Common Problems

Here we’ll look at the most common problems associated with the Chassis system, we’ll list their symptoms, and also if the novice mechanic could realistically undertake the repair.

Corroded or Frozen Brake Calipers

What does it do? The caliper floats across the rotor and when the brake pedal force is applied, the fluid pushes the piston and pad against the rotor forcing the caliper across the rotor applying the second pad.

Faulty caliper symptoms include Sticking brake; Smoking brakes; Hard pedal; Noise when applying brakes.

Can I fix this? Yes, replacing a caliper can be replaced without too much difficulty. However, the brakes will need to be bled before the vehicle is roadworthy. This requires a skill level at the top end of a novice’s ability.

Control Arm Ball-joints

What do they do? They attach the wheel knuckle to the chassis.

Fault symptoms include Uneven tire wear; Vague handling; Knocking over rough ground; Wandering.

Can I fix this? Replacing a control arm can be difficult without the correct equipment. In some cases, many other components need to be removed before the worn-out component can be replaced.

Steering Tie Rod

What does it do? The Tie Rod connects the steering rack to the wheel knuckle.

Fault symptoms include Constant steering inputs needed; Uneven tire wear; Vague handling; Knocking over rough ground; Wandering.

Can I fix this? Worn out ball-joints are common and replacing isn’t too difficult. However, the vehicle will need to be aligned after Tie rods are replaced.

Faulty Wheel Speed Sensor (WSS)

What does it do? The speed sensor reads the speed of the wheel, which the ABS unit uses to detect wheel lock-up. Each wheel has its own WSS.

Faulty symptoms include: ABS light on and ABS system disabled; Traction control disabled; Transmission won’t shift; Wheel speed sensor fault.

Can I fix this? Yes, this isn’t a difficult fix, it is mostly a plug and play, however, first, the faulty sensor must be identified. A code reader is a usual tool.

Worn Wheel Bearing

What does it do? The wheel bearings allow the wheels to turn freely on their axles.

Symptoms include: Humming noise and roughness felt inside the cabin and through the steering wheel and pedals; Possibly an ABS light on.

Can I fix this? Most are non-serviceable. To replace the wheel bearing will take a press and some air tools, this is a job best left to a repair shop.

Electrical Maintenance

The Electrical category covers areas such as the battery, charging, aircon maintenance, bulbs, fuses, etc. The electrical system doesn’t require much in the way of maintenance. However, as a car gets older and as they are packed with control modules, issues do start to arise.

Check Battery Health

Your battery is super important to your car. Latest gen cars run several at least a dozen control modules. All of them must communicate with each other and they do so by sending and receiving voltages high and low.

The modules are really sensitive to high resistance or lower voltages. A good battery is key to trouble-free electrics.

A battery check includes: Checking the terminals for corrosion; Checking the terminals are tight; Checking battery voltage; Load testing the battery.

Check Alternator

Your car battery has two functions, store enough energy to start the engine and start the engine. Once the engine is running, it’s the job of the alternator to produce all the electrical needs of the car.

The alternator’s second job is to replenish battery power, ready for the next start cycle. Check alternator function by starting and idling the engine, turn on electrical consumers like HVAC rear heated screen lights, etc.

Using a voltmeter check battery voltage. A voltage should read in excess of 14 volts.

Check A/C System

The A/C system doesn’t require a ton of maintenance, the refrigerant RF134a will likely need topping up from service to service. A household thermometer in the interior air vent should read 40°F or 5°C with A/C on full tilt, less than this and the system may need a recharge.

Your A/C system includes a pressure sensor, when the A/C control module detects pressure issues, it shuts down the system.

Replace Cabin Filter

The cabin filter or pollen filter lives close to the HVAC, it filters all the air coming into the vehicle and should be changed every year.

Cabin filters are often fitted behind the glove box or under the passenger side dashboard. Some manufacturers and they know who they are, make them sooo difficult to access.

Replace Bulbs

Check all bulbs including brake lights and the rarely used fog lights and lamps. Changing bulbs on late model cars can be a chore, even us mechanics struggle sometimes with the tiny access points.

Rear bulbs are discretely different, the bayonet style bulbs are either straight or offset. Fitting a twin or single will make a difference too.

Check out this post “Brake lights on when headlights are on”.

Replace Fuses

Fuses are wired in series to protect your car and its components from fire damage. Fuses are rated by amperage (A) and it’s important to use the correct rating in a circuit. An incorrect rating could cause some expensive damage.

Replacing fuses is a simple task. Your car will likely have three fuse boxes, one under the hood, one under the dashboard, and a third in the trunk.

A fuse pulling tool is commonly included by the manufacturer, clipped to the rear of the fuse cover. The cover includes a full list and diagram of fuse id number, size, location, and circuit.

pro tip:

Check your users manual for the exact location of the fuse before searching, it will save you a ton of time.
Check the fuse rating in the manual, don’t assume the blown fuse is the correct rating.

Electrical Common Problems

Here we’ll look at the most common problems associated with the Electrical system, we’ll list their symptoms, and also if the novice mechanic could realistically undertake the repair.

A/C System Low On Refrigerant

What’s it for? The refrigerant moves around the a/c system under the power of the A/C pump. The refrigerant turns from a gas to a liquid and back again and in the process removes the hot air from the cabin.

Symptoms of a faulty A/C system, include: A/C switch illuminated and inactive; Cabin doesn’t cool; Windows fog up quickly when wet; Fault code P0530 set.

Is this something I can fix? The A/C system could be inoperative for many reasons, a low refrigerant is certainly the most common reason. However, the low refrigerant could be caused for example by a damaged condenser or leaking pump seals.

If the system is leaking, it will need to be repaired by a pro shop. The system requires special equipment to remove old refrigerant, vacuum the system, add oil, dye, and recharge to specification.

Fuses Keep Blowing

This is commonly caused by an incorrect fuse rating (too small) or a short in the electrical circuit. Electrical faults can be tedious to find, some detective work and a wiring diagram are required, if you like a puzzle, you’ll love figuring out wiring issues.

I wrote a post about reading wiring diagrams here “How to read wiring diagram, beginners guide”.

Battery Keeps Draining

This is pretty common with cars as they age. A battery drain is usually caused by a short to ground, control module that won’t go asleep or a faulty motor. Finding the culprit is a challenge, but we have a few tricks.

The traditional way to searching for a battery drain included wiring a voltmeter in series, but later module-controlled cars won’t like the battery being disconnected. I wrote a post about it here “Car won’t idle after dead battery”.

Anyhow, use the infographic below to help track down the parasite.

Control Modules No Comm

What’s it for? Control modules (Computers) have been in cars for twenty-plus years, in the early days they just took care of fuelling but have proven their worth and are now managing and controlling more and more systems of your car.

Systems like Airbags and restraints, ABS systems, traction control, engine management, Transmission but many of the smaller systems also have their own dedicated controller. Systems like seat modules, door modules, HVAC, Infotainment, etc.

The modules at least a dozen, all need to communicate with each other. They do so by sending and receiving digital messages, in the form of high and low voltages, kind of like Morse code with volt values.

Symptoms of a fault controller: If a control module can’t receive a message, it goes offline and its functions are shut down; Reading the DTC codes will likely display a Uxxxx code and other modules in the system will set fault codes reporting the isolated module as faulty.

Can I fix it? Yes, often problems are easily solved. Most comm issues are caused by high resistance. As said, voltage is the language of the controllers, high resistance in a wire will change the voltage, or an open (broken) wire will simply cut the message off altogether.

Systematically checking all the block connections on the controller and checking for fretting (pin arcing) and pin tension (drag test) will solve a ton of problems.

Use Dielectric grease on the terminals to help protect from moisture, corrosion and improve conductivity.

Body & Trim Maintenance

The Body & Trim category covers windows, doors, roof, trunk openings, paintwork. There isn’t a ton of maintenance here, it’s mostly common sense type preventative care.

Replace Wiper Blades

Replacing the wiper blades is a pretty simple job and they should be replaced annually. Old blades are ineffective, irritating, and will damage the windshield.

pro tip

Buy quality blades, cheap blades are expensive.
Keep windshield clean to prolong wiper blade life and prevent wiper chatter.
Clean your windshield before replacing the the blades.
Apply a product like rain-x, helps clear rain from the window quickly.

Windshield Washer

Fill the washer bottle with washer fluid, tap water may cause bacteria and contain harmful chemicals that cause long-term damage to the pump and clog up washer jets.

Use a deicing formula during the winter, it will help clear icing quickly. I wrote a post all about it here “Water in my windshield wiper”.

Lube Door Locks & Hinges

Door locks and hinges work pretty hard and generally don’t cause too much trouble. But guaranteed, they will last years longer if they are lubed at every service.

White lithium grease works best, it’s waterproof and long-lasting.

Lube Window Rubbers

Dry window rubbers cause friction between the window and the rubber channel. The extra friction is hard on the motor and the regulator. The extra workload shortens both their lives.

You can tell when your window channels need lubing as the window moves slowly or stops partway up and reverses downward.

A spray of silicone lube on the seals will have the window moving like butter, I promise.

Door Seals

Door seals help keep the weather and wind and road noise out of the cabin. When the seals become dry they make a poor seal which causes squeaks and increased cabin noise.

Clean and spray the door seals with silicone lube. It prevents those annoying rubbing, squeaking, wind, road, and traffic noises.

Paintwork Repair

Modern car metal technology is excellent, corrosion is kept at bay for years. The paint tech has moved on too. Many coatings are water-based and not as heavy as older car paint. Paint chips and scratches are still an issue that needs to be fixed.

With a quality, paint match touch-up kit, chips, and scratches almost vanish. This is a job you can easily take care of and you’ll enjoy the results.

Body & Trim Common Problems

Here we’ll look at the most common problems associated with Body & Trim systems, we’ll list their symptoms, and also if the novice mechanic could realistically undertake the repair.

UV damaged Head Lamps

Auto headlamps are no longer glass they’re plastic. They’re made from Polycarbonate injection-molded plastic, they’re tough, impact, and scratch-resistant. However, their weakness is the sun’s UV rays.

The plastic lamps are sprayed with a protective lacquer and baked in an oven. The Sun breaks down the lacquer over time and it becomes cloudy, which obstructs and distorts the headlight beam.

A repair is possible, so long as the lens isn’t cracked. Using fine-grit paper, body rubbing compounds, and a DA buffer, not unlike a paintwork repair, the surface can be restored and relacquered.

Window Regulator Failure

Landrover discovery window regulator removal

What does it do? The window regulator is the mechanism that winds the window up and down.

Symptoms include: Window stuck in the up or more usual the down position; Motor can be heard running but the window either jams or doesn’t move.

Can I fix it? Yes replacing a window regulator is a repair you can make. It is at the higher end of the skill level range however. Check out this post “Window regulator removal”.

Windshield Cracked

A cracked or stone chipped windshield is something every car owner experiences at some time. And when I was an apprentice it meant replacing the windshield, but today we can repair them.

Yes, a windshield crack or chip can be repaired successfully by the novice, but you’ll need to purchase a repair kit. The kit will repair more than one crack so will easily pay for itself over time.

Windshield Washer Pump Faulty

What does it do? It pumps washer fluid from a reservoir through pipework to spray nozzles directed at the windshield.

Symptoms include No spray; Weak spray; Loud noise from the pump; Blowing pump fuse.

Can I fix this? Yes, this is a fix that can be tackled. It may in some cases mean removing the bumper to access the pump and reservoir.

Faded Body Paintwork

This is common in old cars and causes your car to look even older. It’s Sun damage and Red cars suffer the most. But there is a fix, and it really only requires some elbow grease and a few dollars in materials. The results will amaze you and you’ll really enjoy the process, take before and after shots to impress your friends.

I wrote a post all about the process “How to restore faded red car paint”.

Car Repairs You Should Not Do

Here’s a list of car repairs that shouldn’t be attempted by the novice. Some are physically difficult, and some a little complex. Other jobs will require specialized tools or equipment.

Replacing a timing belt or chain, for example, is easy to get wrong and difficult to fix. An incorrectly fitted timing belt or chain could seriously damage your engine and cost thousands to repair.

Timing chain replacement
Timing belt replacement
Replace rear brake shoes
Replace rear brake cylinder
Replace brake lines
Replace suspension springs
Replace clutch plate
Replace head-gasket