Key Fob not starting W212. Battery changed

[PeteK10]

Hi all
I have a 2010 E220 W212
Key fob was gradually starting to not lock/unlock car. Now won't start car. Happened other Key a few weeks ago and assumed it was fob battery. So started using spare key. But same started happening that and then completely stopped working last night. Changed battery in both fobs. Checked fuses and ok. Still nothing. Can anyone help me out with ideas please. Thanks

 

[Oleks1992]

Hi all
I have a 2010 E220 W212
Key fob was gradually starting to not lock/unlock car. Now won't start car. Happened other Key a few weeks ago and assumed it was fob battery. So started using spare key. But same started happening that and then completely stopped working last night. Changed battery in both fobs. Checked fuses and ok. Still nothing. Can anyone help me out with ideas please. Thanks

So just to clarify, both keys won't lock and unlock vehicle aswell as can't start it?

 

[PeteK10]

So just to clarify, both keys won't lock and unlock vehicle aswell as can't start it?

Yep both keys, and won't unlock steering lock. You know the sound it makes when key connects with ignition, it isn't making that sound either.
Thanks

 

[DSM10000]

The battery in the key fob is only there to power the circuit that sends the signal to lock or unlock the vehicle etc.

It plays no part in the key starting the vehicle.

If both keys are not releasing the steering lock then you may have a failed or failing Electronic Ignition Switch

 

[mersum1es]

Does it buzz when you insert key in EIS? If not, you may have EIS servo motor/gear teeth failed. Common problem in W204 and W212, search you tube-

 

[350cls]

Unsure if this will work. But could you try disconnecting the main battery terminals it could do a ECU reset. Maybe worth a try.

 

[Oleks1992]

Yep both keys, and won't unlock steering lock. You know the sound it makes when key connects with ignition, it isn't making that sound either.
Thanks

Ohh that makes sense now! Yeah sounds like you have a dreadful failed ESL fault, you'd need to check fault codes to confirm though

 

[PeteK10]

The battery in the key fob is only there to power the circuit that sends the signal to lock or unlock the vehicle etc.

It plays no part in the key starting the vehicle.

If both keys are not releasing the steering lock then you may have a failed or failing Electronic Ignition Switch

Thanks will check that out

 

[PeteK10]

Ohh that makes sense now! Yeah sounds like you have a dreadful failed ESL fault, you'd need to check fault codes to confirm though

Ok, will get it plugged in with mechanic. Thanks

 

[PeteK10]

Does it buzz when you insert key in EIS? If not, you may have EIS servo motor/gear teeth failed. Common problem in W204 and W212, search you tube-

No buzz sound anymore. Will get this checked out. Thanks

 

[PeteK10]

Thanks for all the help. Had an auto electrician out and he was confused because the keys were doing nothing at all. Just the red light flashing on them. Anyway, he ended up re programming both keys and seems to be ok now. Hopefully that lasts though and not an ECU intermittent fault