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Hi all, would appreciate some help
I have a 2008 CL63 55,000 miles, amazing car, but seems to be a little upset
Jan 2024 I had all 4 ABS speed sensors replaced as had an ABS fault, and after that was fine
Then in October 2024, a new issue came up, when the car is turned on it is perfectly fine no faults, everything works as it should, however once you get over about 15mph, all hell breaks loose. The car shuts of everything speed related, so no power steering, ABS / ESP off, parking sensors inactive, cruise control inactive etc, but you can still drive fine.
If you then stop and cycle the ignition, all car goes back to normal, in Dec 2024, the issue then completely went away, stick a diagnostic machine on it, no faults, or histroy etc, so happy days
However in April 2025 the same issue has come back, i've had the car checked on a diagnostic machine and the fault does not come up, but same issue, start the car all ok, over 15mph all speed related systems shut down, cycle the ignition and everything is golden again.
Any ideas would be much appreciated, I can only assume it my be an issue with one of the speed sensors that where replaced.
Last edited by Aurora63; Jun 17, 2025 at 09:48 AM.
My first guess is some kind of short or electrical fault. If it were a truck, I'd lift it up on a jack, start it, then drop it off the jack to see what happens. Alas, this is not a truck. I'd also check all the ECU/TCU plugs. Check fuses for corrosion, check wiring diagrams and see if those systems share power or a ground point somewhere.
You also might start it, open the hood and trunk, and jump on the engine brace and in the trunk itself to see if it causes the same issue. Probably not, but easy enough. You can also jiggle the wiring harness (anywhere you see wires) with the car running and see if you can get the error to happen without driving.
All the diagrams I see in the WIS for that particular year indicate your culprit might be the ESP control unit (N47-5), which receives vehicle speed from the 4 wheel speed sensors and outputs a speed signal to a bunch of other systems such as power steering:
Sounds dumb, but did you try recycling the ESP switch while driving to see if it clears anything?
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