District Benz

Hi All,

I just had the front passenger (left hand drive car) wheel bearing replaced. My indy shop called me after he did the replacement because after it was done it was throwing a code for the front passenger side ABS sensor, along with an associated dash warning "BRAKE ABS ESC Inoperative" message. He ordered a new ABS sensor from the dealer and replaced it yet he still can't get the codes to go away.

Along with this repair he also did the rear air shocks and the engine and transmission mounts. I had to pick up the car since I need it for Thanksgiving and the shop was about to close, but it drives beautifully now and is super quiet sincet the wheel bearing has been replaced, but there were no warning lights or codes after the mounts and shocks were replaced (he drove the car after finishing those repairs when he notified me of the wheel bearing which I thought was just a loud tire(s)). Thought I'd mention those other repairs but it seems like the warning lights are as a result of removing the wheel and sensors to replace the bearing.

My indy shop has the proper tool to reset the codes which worked for about two seconds, they immediately came back on when driving. Any idea what's wrong? He seems to be stumped... might the replacement ABS sensor be a bad sensor or could it be something else? This very frustrating after spending so much money and having the car drive so well, only to have this problem that doesn't go away with a new sensor. Thank you!

Sunnyslope48

Replacing the ABS sensor often solves the problem, but not if there is another circuit problem. You need properly function sensors AND the circuits must also be electrically sound. The indy should have the tools and knowledge to find and correct the problem. If he does not, you'll need to go elsewhere.

fc3

Wrong hub, bad or missing reluctor? Put a DVM in frequency counter mode, or 'scope on the output pins of the ABS sensor, then spin the tire. You should get an AC voltage of varying frequency which you can read. That's about as basic of a test as you can get, but it is quite reliable. I used that same test to fix the ABS on my 1972 Imperial LeBaron. Sometimes old school is best. Or simply do a visual inspection of the reluctor ring. It should look like the original or the one on the other wheels.

Arrie

Did the shop just damage the connection harness for the sensor and the sensor itself was just fine?

cetialpha5

Did they dislodge a seal or replace one? This was a common problem on the W211, only the MB part worked, the aftermarket ones weren't quite right. Search for seal and ESP on the W211 forum. Either the seal didn't line up or was knocked off alignment or it was an aftermarket part. The sensor was normally fine, it's the other piece that's off.

District Benz

Thanks, I'll have the shop check the circuits tomorrow to see if they're sound. It's annoying to have so many lights lit on the dash and no cruise control is the pits.

District Benz

Thanks for the info, will print this out and will have the shop check what you have suggested.

District Benz

Which seal do you mean? The mechanic is on the phone with me now wanted me to ask.

He noticed the impulse ring (or reluctor ring) was damaged and he replaced this (he actually replaced the outer CV joint since the ring along isn't available), allt he codes are still illuminated!! Very annoying...

District Benz

He replaced the reluctor (or impulse ring as he calls it) and still no luck (he actually replaced the outer CV joint because the ring wasn't available on its own). Any ideas? Very frustrating...

cetialpha5

Did he replace it with an MB one or aftermarket? The aftermarket ones can give you problems, people sometimes replace them several times til they use the MB one. Plus if it's a little off, it will also cause problems.

District Benz

He replaced with a Mercedes part, both the outer CV joint and ABS sensor (last week) that he got from the dealer.

Which sensor do you mean?

Also, the mechanic is wondering if the system needs to be reprogrammed after the repairs were done. He’s got a Maxidiag scanner which isn’t resetting the codes, is another scanner needed or does it need to be reprogrammed?

cetialpha5

I was referring to the reluctor/impulse ring. But that sounds like he used an MB part. W211's didn't need to be programmed, but I don't know about W212. Could also be damaged, not flush, too flush etc. When the sensor is fine, it's usually the ring.

District Benz

So the mechanic checked the sensors and the wiring harness which he says is all fine but the codes still won't go away, he also says he checked the ring and that it's on properly. I think I'm just going to have to "eat crow" and take the car to the dealer tomorrow, my usual guy is just really stumped and I've been without the car now for over a week. If you have any last minute ideas I'd be all ears! Thanks...

modar

The battery may need replacing

CaliBenzDriver

2019 was 5 years ago..
I bet he got it replaced by now