C207 locking/immobiliser

[Carrotchomper]

This car constantly finds new ways to try my patience!

Anyway, sometimes the key fob won’t open car on first press. Then when I put the key into the ignition the steering lock comes off perfectly, but sometimes it won’t start and comes up with “ESP inoperative” message.

re-locking and unlocking the car with the fob and it’s generally fine.
I guess it’s the immobiliser not disengaging, but is it likely to be a key fob issue or something else? I have changed batteries before and the range of the key seems better, but it’s short lived.

do they need a certain battery, ie premium brand?

 

[AndrewOl]

You are best with quality batteries like varta or genuine mb ones. The keys have an IR section that does all the opening and closing stuff. There is a different circuit in the key that does the starting. Sounds odd that both are acting up. Have you a spare key to try? The obvious thing is to plug a scanner in to see what codes are present, sounds like there will be. Even better would be a Star diagnosis. Should help you pinpoint what is going on.

 

[Carrotchomper]

Thanks Andrew. I think it is the opening/closing circuit which is the issue, the detection of the key in ignition is fine. I’ll try my spare key and see if that’s different.

 

[AndrewOl]

I recently killed the ir functions on my key when I dropped them. My type of fob doesn’t come apart easily so I sent it of to some guys who fixed it for £35. Details are in the thread.

 

[tonysmb]

As already suggested, it's definitely worth using 'premium' batteries in the handset, the MB-branded ones I've had have been Varta. The spare key/handset should confirm whether it's a key or car issue.

I've previously found that when a remote doesn't seem to be working properly (probably through lack of use, on another car), holding the 'lock' button down for a few seconds (say 5) seemed to reset things. Might not work on the MB, of course.

 

[Carrotchomper]

Now on spare key, so we‘ll see how that goes!

 

[Carrotchomper]

Nope, spare key behaves the same. Next I’ve got decent batteries ordered.

interestingly though, today I stopped briefly on the way home. Didn’t lock car. Got back in and same fault came up, had to lock and unlock to restart??

 

[AndrewOl]

Unlikely that both keys are duff but worth ruling out something silly like batteries. I would be getting a star diagnosis from an indie to see what was going on. There must be codes stored. I take it you don’t have an OBD scanner?

 

[Carrotchomper]

New key battery has made no difference. I have noted that the glow plug light doesn’t come on when it’s in a ‘no start’ situation, is this also controlled by the immobiliser?

I only have a very basic code scanner, friend may have a better one I could borrow.

its a trek to the Indie so keen to try everything I can first.

 

[andy27168]

Hi
Does the key release the steering lock every time?
Does it turn in the EIS (Electronic ignition Switch) every time?
As it sounds like you have a failing EIS or possibly the ESL.(Electronic Steering Lock).

 

[Carrotchomper]

Thanks all. Friend came round and we diagnosed low battery voltages, dropping to 9v when starting. So new battery in. Problem has been still happening, although we are hoping now it’s a residual fault from poor battery…loads of random codes were stored which have now been cleared.

Failing that it’s ignition out!

I am wondering though, if the EIS was failing surely no lights would come on at all when trying to start?

 

[andy27168]

Hi
I have similar issue where my cluster goes completely dead, and there are other non operating things as well, the worse bit I can't switch the engine off until I take the keyless button out and put the key in I don't need to turn it in fact it wont and the engine shuts down, refit the keyless button and it starts up ok.
I have it initially diagnosed by my indy as a failling instrument cluster, faulty EIS or central gateway unit (this unit is integrated with the EIS).
Because of the possible expense of an EIS is would get someone to plug it in and see where the issue is and where the CAN signals are getting blocked.
Though as you have cleared all the stored codes this might be a bit difficult now as youre fault is intermittent.

 

[Carrotchomper]

Interesting…

…fingers crossed this problem hasn’t recurred. Loads of rear SAM related errors were coming up. Friend found several chafed/almost broken wires on the boot loom. Now repaired.

Seems to have worked, although boot button now doesn’t. We think that’s due to water ingress on the rear brake light!