Key Fob Not Locking/Unlocking/Starting Car

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New Member
Apr 19, 2021
Mercedes-Benz CLC 1.8 Kompressor

Recently the proud owner of a 2010 MB CLC 1.8 Kompressor manual. Currently trying to sort out an issue with this car that has left the RAC and my dealer baffled.

So took it for a test drive a few days ago - everything was kosher. Key fob was working as expected. I went to unlock the car yesterday but had no response from the car. It doesn't matter if I'm 20m or 1m away from the car nothing happens.

So I pulled the mechanical key from the fob and used that to unlock the car, thinking the fob should still work if the battery was dead (which is what I initially suspected). The alarm went off as expected, so I put the fob in the ignition and... nothing. The steering lock does not disengage and I cannot turn the key.

Eventually (and rather embarrasingly) the alarm finally went off; the hzards were still flashing for a few minutes but eventually they went off too. So, sat in the car in silence I remove the key fob and reinsert, and still I get nothing from the car. The radio works, but every other function is dead. The Anti-tow button on the dash is flashing red every second.

I call the RAC out who checked the key battery (all fine), and says he's not receiving an IR output. (Strangely though if I point the key fob into my camera, I can see the IR illuminate along with the red light.) The RAC guy checks a few fuses, tries jiggling the steering wheel with the key in, and gives the car battery a clean bill of health, and reseats the battery connectors too. At this point he recommends a new key fob.

So I call the dealer who agrees to replace this free of charge (currently waiting for them to come and replace the key fob). However doing some research online I've come across a few possible leads:

The number 8 fuse in the boot may've blown - I've checked this and replaced the fuse and still have the same issue.
The anti-tow alarm in the boot may be kaput - something I don't want to check as it's still in warranty.

The current state of the car is it's sat on my driveway, silent and no hazards flashing, with the anti-tow button on the dash flashing. All the doors are unlocked and you can't lock them. Whenever you open any of the doors or the boot, the alarm goes off for 30 seconds, flashes the hazards for a few minutes, then goes silent.

Has anyone come across this before? CLC is a rather rare car to find info about online.

Many thanks in advance

For anyone that stumbles across this thread, this is now resolved. I had a key company come out. He said the key that came with the car was a cheap aftermarket one (you can tell as the circuit board was white and not green). He programmed a new key for me, and reprogrammed the old key and now they're both working.
Welcome and well done,so the old key lost it's programme
Welcome and well done,so the old key lost it's programme
Exactly, it had lost it's programming. When he put the key in his machine it had no data on it. He said this can happen with cheaper keys. At least I have a spare key now and the dealer paid for the new one! Happy days.
All Mercedes cars have around 6 key numbers built into the car,so the key guy picked one that had not been used and put that on the new key and reprogrammed the old key at least it sorted out the problem and the garage payed for the new key so all is well.
My dad has a 2010 CLC 180 Kompressor and this exact thing has happened today!! Which key company did you use?
Well there are lots of car locksmiths who can replace mercedes keys,going by your locale in Norwich autolocksmiths have a branch there,doubt if you will get much joy on a sunday afternoon,look online you should find somebody.

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