When the Key Fob Has Power but Still Won’t Work: An Audi A6 Mystery Solved

There’s a certain look on a driver’s face when they’ve done everything right and the car still won’t play ball. That was the case last week when I was sent to help an MBR stranded outside a busy mall, kids in tow, rain bucketing down, and her Audi A6 refusing to unlock.

She’d already replaced the key fob battery herself—smart move—and even knew how to access the manual key barrel by removing the little tab on the driver’s door handle. Only problem? She couldn’t turn it. Years of grime and neglect had seized it up.

The Right Call at the Right Time

When I arrived, I found her waiting at the mall entrance with the little ones in tow. I told her, “Go get a coffee, I’ll call when I’ve cracked it.” No sense standing in the rain when I’ve got tools and patience to spare.

Step 1: Rule Out the Usual Suspects

First thought in these situations? Two likely culprits:

1. Dead key fob battery
2. Flat car battery

But this MBR clearly knew her way around the basics, so I leaned toward the latter.

I took cover inside the van and checked the key fob—sure enough, the red light came on when I pressed unlock. That tells me the fob has juice. So now my suspicion shifts to the vehicle’s 12-volt battery.

I worked the door lock with a little WD-40, got the door open, and hit the Start button—“Key Not Detected” lit up the dash.

Step 2: Battery Check—But It’s Not What You Think

Modern cars are fussy. Sometimes, even a healthy battery that’s dropped a little voltage under load will trip up systems like keyless entry. I popped the hood, alarm screaming in my ears, and checked the voltage: 12.6 volts. Rock solid. That wasn’t the problem.

Step 3: Finding the “Hot Spot

Here’s the thing with smart keys—they all have a backup reader, usually called a “hot spot,” for when the fob won’t transmit. Most cars tuck it in a cup holder or under the dash. Usually, there’s a little embossed key symbol to give you a clue.

Not in this Audi.

I tried the common tricks—pressing the Start button with the fob, holding it near the cup holder, even tried a few dash locations. Nothing. No joy. So, I did the thing most techs only do as a last resort: I cracked open the manual.

And there it was: the hot spot on this model is inside the centre armrest. I held the fob at the front of the now-open centre armrest, hit Start again—and she fired right up.

The Diagnosis

In this case, the fob had battery power but wasn’t transmitting the signal. Likely a failure in the internal transmitter circuit. I asked the MBR if she had a spare key—thankfully, she did.

I advised her to use the spare for now and said this one could probably be repaired at a small electronics shop that handles soldering and circuit board work. No need for a dealer replacement just yet.

Northcap’s Tip

Just because the fob lights up doesn’t mean it’s working.

• A working battery doesn’t guarantee the fob is transmitting.
• Sometimes, the solution is buried in the glovebox—in the owner’s manual.

Know where your key hot spot is. Try the spare key. And if you’re stuck in the rain with tired kids, don’t be afraid to call for help. We’ve all been there.

– Northcap