When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello MB World Forum!
I've been watching the forum pretty closely since I got my 2011 E350 Wagon 4Matic several years ago. The group has helped me quite a bit with various repairs, like brakes, thermostat, air springs, and alternator/belt repairs just to name a few. All in all, I think this group has saved me at least $10K based on prices from my local dealer. So, first and foremost, thank you!
My newest issue is a bit of a puzzle. I'm seeing the following lights and error codes, even after replacing the Left Rear Speed Sensor. These errors pointed me pretty squarely to a failed speed sensor, but apparently, I was wrong. Looking for some advice on where to go next, other than to the dealer! Before replacing the speed sensor, I checked fuses closely. My research told me that #1, 14, 20 were all related to ABS/ESC. All looked AOK. Also, the scanner is an iCarSoft MBII, recently updated to the new firmware.
Thanks for the information. This is the exact repair I just finished. Replaced the Left Rear Speed Sensor prior to the photos and scanning above codes. ABS/ESC Inoperable still persists.
Thanks for the information. This is the exact repair I just finished. Replaced the Left Rear Speed Sensor prior to the photos and scanning above codes. ABS/ESC Inoperable still persists.
After sensor replacement did you reset the error codes is all modules you have them? In my S-class I had the left front speed sensor go bad and it lit up the cluster like a Christmas tree. After replacing the sensor I reset faults in 5-6 modules. After that all good.
i haven't looked up the procedure on these cars, but every car I've had before with wheel speed sensors, you need to gap them with a feeler gauge so they are just the right distance from the 'tone ring' they read.
Assuming speed sensor is genuine and healthy, if rear left and right one can be swapped, do the swap first.
This will confirm integrity of wiring connection being good or bad.
When later you want to further investigate voltage/power reading on the sensors, do be careful because some wheel sensor system will auto shutdown if it sensed sensor problem.
This means you seems to not get power to the sensor because it was cut off by the system/computer and not because of bad wiring.
Recycle the starter key, OFF a few seconds and system will reset. Some system only allows 1-2 seconds of sensor failure and then it cuts power off.
I can report that it was not a genuine part that I used… I’m starting to think it’s a possibility that the part was bad out of the bag or is somehow incompatible with the car. I’ve been buying most parts from Rock Auto, maybe it pays to go genuine with this one. I’ll order the Merc speed sensor and report back…
that said, when I searched rockauto for the Mercedes PN on that "Holstein" ("Cow"??) package I noted both a Bosch and Hella PN on there for just a couple $ more than the Holstein. I'd probably eyeball the original factory part and see if it has either Bosch or Hella logos along with the Mercedes tristar.
Bosch Hella
Last edited by Left Coast Geek; 02-21-2022 at 05:00 PM.
Unfortunately, I just replaced the Rock Auto Sensor with a Bosch from FCP Euro, which had the Bosch markings as well as the Merc Star logo on the plug end, and no difference. I’ve cleared all related faults, test drove the car, and they all came back within minutes. Faults are identical to those in my original post. Any ideas where to look next? Any help is appreciated. Thanks.
Move on to pulse (reluctor) ring that sends signal to sensor. EPC shows these part #s for 2011 212.287 however, some online sites are claiming they will not fit, VIN?
I assume the difficulty is in removing suspension arms and getting the hub off axle end. Are there any ways to press this ring on without special tools?
Just wanted to report back that the pulse ring was indeed the issue. When I got everything apart, I saw that the magnetic layer of the pulse ring had separated completely from the metal ring. I had to peel the magnetic strip out of the inside of the hub assembly. So, as the wheel turned, the ABS sensor recorded no movement. I purchased the new ring for $30-ish from FCP Euro and spent about 5 hours in the garage completing the job. An unplanned complication was the amount of rust and condition of the park brake springs in that wheel, so I changed all that too. I now have the right side park brake on my to-do list. All in all, it wasn't a fun repair, but wasn't difficult either. I do appreciate the guidance that this forum offered me through the process. I'm guessing it just saved me another $2,500. Thank you!
Eric O. from YouTubes' South Main Auto channel has several videos on diagnosing wheel speed sensors. In this video he put a scope down the speed sensor hole to take a look at the tone ring which seems like a good thing to try before pulling everything apart. He also uses an oscilloscope to diagnose as well.
02-19-2022, 04:52 PM
