ABS, ESP and other lights

[the red barron]

Hi all, not had to ask a question on here for a long time since changing the C220 for a C350. I have a ongoing problem with the warning lights coming on for ABS etc. This is whats happening, start the car in the morning numerous messages come up saying something like "run flat indicator inoperative", "ABS ESP inoperative". Took the car to our local Indy who put it on his diagnostic machine which said L/H front wheel speed sensor faulty, replaced wheel speed sensor which changed nothing. Back on diagnostic machine, same message L/H front wheel speed sensor fault, replaced with another new wheel speed sensor, messages and lights gone for a short while (4 miles) which was the journey home. Strange thing now is when the car is first started in the morning up come the warnings and lights drive for 2 miles switch off and leave a couple of minutes and no messages or lights and the car runs fine until the next morning when it's the same again. Lost confidence in our Indy a bit so may have to go to the main Stealers. Sorry for the long post, any suggestions?

 

[Blobcat]

Is the replacement ABS sensor a genuine Mercedes one ? Quite a few issues with aftermarket ones not reading correctly.

Also has reluctor ring rusted off or are the holes blocked?

 

[Mark A]

Give the battery a good charge, a weak battery can throw up all sort of warnings. Was your indie using STAR or was it a generic code reader?

 

[Wearsafoxhat]

Is the battery in good condition.
Think that the brake pedal switch is part of that circuit too.


Sent from my iPad using Tapatalk

 

[the red barron]

Thanks for the replies, the battery was replaced approx. 6 weeks before this problem manifested itself. The ABS sensor was purchased by myself from the main Mercedes dealer. The diagnostic machine used was a Snap on machine, flash bit of kit. Wearsafoxhat i read about the brake switch last night, will try that next.

 

[mioba]

Consider what Blobcat said re rings

 

[Mark A]

Even a name brand such a snap-on won’t give them the same level of diagnosis as a dealer / indie with the right kit STAR.

can anyone recommend a good indie near Swansea?

 

[the red barron]

Consider what Blobcat said re rings

The w204 doesn't have reluctor rings as such, they have magnetic lip seals.

 

[bembo449]

You really need to confirm the rings are in servicable condition as the chaps have suggested , pretty much every MB with a similar problem to yours i have dealt with its been the ring at fault

 

[LostKiwi]

Check the gap between the lip seal and sensor. More than 1mm will give bad readings.

 

[supernoodle]

A fault code should not trigger an automatic replacement of a part. Especially not twice.
You have to consider all the components in the circuit or system identified. So as others have said, for a wheel speed sensor that is everything from the mechanical part that triggers the sensor, the sensor and the wiring up to the module that is processing the signal.

The same holds true for all faults. Often see comments on here, I got a fault, replaced the sensor /actuator and still have got the fault.

There's usually some way of testing before having to replace, whether that be swapping around parts when there are multiple on the vehicle like wheel speed sensor, signal generators or using an oscilloscope. Some of it may be beyond a home mechanic but a decent auto electrician should be able to test and know common failure modes to check first.

 

[the red barron]

Thanks for the replies, problem still exists so may have to take a trip to main dealer.

 

[LostKiwi]

Forget the main dealer - all they will do is replace parts because the computer says so.

You're not too far from Avantgarde Motors run by @Steve@Avantgarde on here - a very highly respected and knowledgeable Mercedes Specialist.
Book it in there and have him look at it.

 

[steveq]

As others have said, the new error message might be related to the LH sensor but equally well might not be.

I had a front wheel speed sensor fail on my W204, replaced it and the error cleared.

I did write it up here and some of the professionals who are on here recommended that I replaced both sides. That makes sense for them as a) both sensors are the same age so the other side is more likely to fail, b) when they have the car in the workshop it is easier to replace both sides and c) the client won't be giving out when the error reappears very soon after replacing just one side.

About a month after I replaced one side the same fault reappeared -- typical !!
However, this time it was the sensor on the other side front wheel.

I was doing it myself on the driveway so there was no big deal in replacing them as two separate jobs.

I would suggest that you get an OBD II reader -- many on here have iCarSoft readers.
It can show the live speed readings from each wheel as you drive. That is what I used to identify the fault.

Replacing the wheel sensors is a simple job with the most difficult part being the removal and refitting of the plastic liner in the wheel arch.

Identifying and resolving one single fault yourself will repay the cost of the OBD reader.

 

[Altamar]

Even a name brand such a snap-on won’t give them the same level of diagnosis as a dealer / indie with the right kit STAR.

can anyone recommend a good indie near Swansea?

Thanks for the replies, problem still exists so may have to take a trip to main dealer.

I have used MB Specialists in Bridgend a few times and find them great. I think they were main dealer trained and then set up on their own.

01656 647864

 

[mioba]

Bet its the other side, I had the same on my W220, replaced one side, other died a month later, also dont use aftermarket, they will die in 8 months.

 

[the red barron]

Hello again, the car is booked in to be looked at on the 16/11. Thanks for replies/ suggestions, Mioba 2 diagnostic machines both keep saying l/h front wheel speed sensor. We will see what happens next week.

 

[mioba]

Good stuff hope you get sorted. The hole needs to be cleaned (as in WIS) rings good and gen parts.
If that doesnt solve, then it could well be the ECU. Also had that on my W220.

 

[zedmeister]

I had a problem with brake switch throwing up similar errors - cheap and easy to replace behind the brake pedal. It would only do it after some driving and not immediately after starting.

 

[the red barron]

Here is a update on what's happened since my last post. The car was due to go into the garage on the 16th November but due to Covid in the workshop this appointment was cancelled until further notice. Last weekend 21st November i decided to try something myself, i purchased a Draper Expert diagnostic code reader, plugged it into the car and up came the message L/H wheel speed sensor - no signal. This diagnostic tool has a live data function showing wheel speed data so me and my good lady wife took the car for a short drive and sure enough on screen showed no rpm's from l/h front wheel. Doing a bit of logical thinking i decided to swap the wheel speed sensors from left to right to at least eliminate the wheel speed sensor ( If it was the wheel speed sensor the problem would now be on the r/h front wheel). 2.5 hours later, one side of the car at a time the swap was done and to my utter amazement we now have no messages and no warning lights, the car is back to how it was 5 weeks or so ago and has been perfect for the last week. No visit to the "stealers" no more new parts ( the Draper Expert code reader was a bit expensive though but can be used on other vehicles in the family). If any of you guys can cast any light on why this has happened cast away.