Key fob stopped working

[Vincenzo13]

Hi all my key fob just went dead!battery light flashes,infrared light works,but nothing?yet my spare key locks unlocks and starts car?any ideas cheers

 

[Stevie1982]

If you've replaced the battery then possible Ignition Switch starting to play up?

 

[AndrewOl]

Assuming you have tried a new battery then it is worth checking if it is just the ir section that’s damaged. If the key will still start the car but just won’t unlock it then it’s the ir section. If that’s the case then it can be fixed. New mb keys are expensive so if you don’t fancy that maybe try one of the mail order repair people. I used one when I dropped my key and it stopped working.

 

[ChrisEdu]

Try with your spare key; that should indicate whether or not it's a key issue or something else.

 

[Vincenzo13]

Try with your spare key; that should indicate whether or not it's a key issue or something else.

Yes Chris spare key works,so obviously key?but how do I get old key to work?any ideas appreciated

 

[ChrisEdu]

Hmm.....weird. I wonder if it's possible for the coding to somehow become corrupted?

 

[Diesel Benz]

The OP has provided a reasonably good description about the problem but still some details would be useful. Which car is it, a C-class as in the signature but which MY? Keys are completely different on the current C compared to older models. Is it a Keyless Go key? The misbehaving key does not open/close door locks, neither starts the car?

Assuming it is the 204 series type "normal key" and does not operate locks, neither starts the car with the key in the ignition lock, the problem indeed sounds weird. It isn't the IR led as the OP has tested it. It isn't the power coil as it would not affect door locks, just starting the car. It does not seem to be a stuck key switch as the OP would have observed that when testing IR. Battery is not needed to start the car although it seemed to be OK. If the key coding was corrupt, the car should give a "wrong key" warning at the cluster (W204 and newer).

 

[Petrol Pete]

Hello and welcome . Did you use a high quality (Duracell etc) battery ? or one from those cards you get at Poundland with 30 coin type cells stuck on it for a a quid ?

I use both , the cheap ones for kids toys/Xmas lights and (rather more expensive) Brand names ones in the key fobs. Some people say they are all the same , but that has not been my experience.

let us know how you get on

 

[Vincenzo13]

The OP has provided a reasonably good description about the problem but still some details would be useful. Which car is it, a C-class as in the signature but which MY? Keys are completely different on the current C compared to older models. Is it a Keyless Go key? The misbehaving key does not open/close door locks, neither starts the car?

Assuming it is the 204 series type "normal key" and does not operate locks, neither starts the car with the key in the ignition lock, the problem indeed sounds weird. It isn't the IR led as the OP has tested it. It isn't the power coil as it would not affect door locks, just starting the car. It does not seem to be a stuck key switch as the OP would have observed that when testing IR. Battery is not needed to start the car although it seemed to be OK. If the key coding was corrupt, the car should give a "wrong key" warning at the cluster (W204 and newer).

Hi it’s a 58 plate c class 2.2 diesel,I’d pulled up outside my house and pressed the lock on remote,nothing,so put the key in ignition again nothing?went and got my spare key and everything worked!the bit that holds the batteries I took out and that worked in my ‘spare’key?so it must be my original key?baffled I am cos there was no warning?