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W204 P0123 throttle / pedal position sensor switch a circuit high

Old Jun 21, 2021 | 07:07 AM
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C Class 2011
W204 P0123 throttle / pedal position sensor switch a circuit high

A month ago my engine light came on I plugged in my OBD reader and got the above error which I cleared.
A week later I mentioned it to a mechanic who plugged his reader in and the error was there again even the engine light was not on.
He said its the throttle body which needs replacing and quoted me £350 to £400 for the work to carried out.
The car is running perfectly and I have driven 900 miles without any probs at all, the engine light is still off but if I plug my OBD reader in th error is still there if it's cleared it reappears after a while.
I have googled and searched here the error and see that there is a few things other than the throttle body that could cause the problem including the sensor in the pedal a broken wire or a short and a dirty throttle body housing.
Now I feel a bit dubious about the quote I was given as all other the other fixes could be somewhat cheaper.
Does anyone here know of a way of diagnosing the fault further or should I just leave it and see what happens..
If it turned out to be the pedal I could prob change that myself.

I have tried the throttle body reset mentioned in other post on these forums which has made no difference.
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