Starting Problems-C240 Sport

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New Member
Sep 16, 2008
C240 Sport
I have recently joined the MB club with my first MB a lovely C240 Sport 98

Unfortuantely i have a problem every now and again which is the engine won't turn over when trying to start it. Sometimes just a delay for a few seconds before re-trying sorts it out. Both keys have the problem although one is a lot worse than the other.

Do you think this is just the key batteries requiring replacing or does it point at a more sinister issue?
It's not key batteries, the batteries only do the central locking. Starting is powered by an induction coil in the switch.

Assume there is a click then you insert the key and then turns OK?
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When you insert the key and turn it, you get a click but it doesn't sound like a starter motor click and the next time it starts, not always the next time but it does start.

I wondered whether the key was operating an immobiliser when it is inserted and this was not getting switched sometimes by the key.
I was thinking of the initial click not a starter soleniod type click. Anyway if the key turns OK that shouldn't be an issue.

There isn't a separate immobliser as such, the switch (DAS) is fully electronic. When you insert the key the switch reads the code from the key if the code/sequence match the switch the key can turn and the car be started.

I'd start at the other end, starter motor contacts etc. I've not had the problem, but I recall mention of starter ring sticking (not sure it that was on the M112 engine though).
Although you say one key is worse than the other! Odd because if the key is not recognised it won't turn (I think - I have a duff key I'll check that)

Still might be worth cleaning the window in the end of the key (and the switch).
I'll try cleaning the key and the wee window bit. With the key turning though I guess as you said that the key is probably good. I'll get the starter checked out and move backwards from there.

Cheers for that.

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