Key Fob not Recognised

[SoulfulStevieD]

Hi Guys - I have two key fobs for my SL55 AMG 2003. Both worked fine and now one will not let me in the car or start once inside using the mechanical key, with the alarm triggered. Changed batteries twice but made no difference. Fob light and led working as normal. Is there a way of re-syncing the affected key? Thanks in anticipation.

 

[SpikyMikey]

Hi Guys - I have two key fobs for my SL55 AMG 2003. Both worked fine and now one will not let me in the car or start once inside using the mechanical key, with the alarm triggered. Changed batteries twice but made no difference. Is there a way of re-syncing the affected key? Thanks in anticipation.

Duracell batteries by any chance?

 

[SoulfulStevieD]

No Panasonic

 

[MSG2004]

Could be a weak car battery - how old is your battery and do you drive the care regularly so it warms up and able to charge the battery?

Other than that as you've already changed the key battery, its a faulty key if your other key is opening the doors and allowing you to start it.

See what others suggest (Sorry to ask a silly question, are you sure the key batter is in the correct way?)

 

[SoulfulStevieD]

Yes the car batteries are good - drive the car most days 40+ miles. The fob does light up to prove it is in correctly. One fob works the car, the other doesn't - all of a sudden.

 

[MSG2004]

Yes the car batteries are good - drive the car most days 40+ miles. The fob does light up to prove it is in correctly. One fob works the car, the other doesn't - all of a sudden.

Thanks. I doubt then it is your car battery, but if it's old ie more than 7 years old, get a health check on it but TBH, I doubt its that

The only other thing I can think of is a faulty key or worse, ie ignition system. However, as I post this and as your other key works, IMO its your key that is at fault


Edit
I recall one of our children's car keys not working on their MB years ago and vaguely recall them saying they did something to it - a procedure - so I type in Google for key reprogram and found this from this site - it may not work but give it a go

G

Thread 'How to reprogram electronic key fob'

Sep 7, 2010

The key I normally used stopped working some time ago and when I finally got the battery changed, the key no longer worked. I called a Mercedes dealer who said that I had waited too long before changing the battery and that the key now needed reprogrammed. They wanted to charge £100 for this. (As far as I can tell, the key does fire out a signal. I tried the trick with pointing the key at a camera to look for the flashing light which is rapid and strong).

I spoke to someone at a garage specializing in Mercedes and was given a set of instructions, which I have also seen since on e-bay...

• GlenAffric
• electronic fob key reprogram
• Replies: 8
• Forum: Electronics and Audio

 

[SoulfulStevieD]

I have tried the key in the ignition trick but as the key will not turn, this does not work. I will try a specialist then buy a new key if needed. Thanks for the advice thus far.

 

[KillerHERTZ]

Has it ever worked? Is it even the correct on for the car when you bought it/dealer error?

 

[SoulfulStevieD]

Yes, they both worked with no issues and I was leaving the office last night when the fob I was using wouldn't open the doors. Once in the car with the mechanical key and the alarm blasting away, the car would not start using the gear button or even turn in the ignition. First time the key fob has failed. Dash says 'Key Not Recognised' Once my wife delivered the spare fob - I was able to run the car normally. Once home I changed the fob battery twice but even though the light and led are working on the fob, the car does not respond.