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I have a 2014 E550 with ABS and a bunch of other lights on the dash. Only code that shows up is faulty right rear wheel speed sensor. When I looked at the run time data (standing still or driving) it it pegged at >40000mph on my scan tool (YOUCANIC UCAN-II-B PRO). Does not change at any speed or standing still.
I replaced the sensor thinking it was logically the issue but that didn't help anything. Anyone run into this before?
magnetic tone wheel at the wheel bearing rusted away........ so your sensor can't read any signal and that 4,000mph is probably the max numeric limit of the software
Thanks, That is where I was headed next, but I wasn't sure if that problem would exhibit this symptom. Given that it is somewhat of a PITA to get to that magnetic ring I didn't want to dive into it unless that was a possibility. Is there a way to check the harness to ensure I don't have a short somewhere? How about the sensor itself (resistance or something?)?
The only way to test if sensor is pumping out signal is using oscilloscope.
To test magnetic signature of bearing is easy, buy those magnetic paper/plastic, but you must do teardown to access the bearing first.
At the least swap left to right (rear sensor ) with extension cables and physical sensor position change, this way u also test wiring harness integrity.
Alright, getting back to this after being on vacation for a while. Anyone know where the wiring routes from rear of car to front? I was thinking of extending the wiring of my original sensor to allow it to connect to the left side to check if that then reads properly to determine if the mag ring is bad on the right rear wheel side. If that doesn't resolve the crazy signal on the right side I can only assume there is a wiring issue on the harness side. Is there any voltage/resistance check on the harness side of the wiring?
Last edited by DaveW_396; Jul 7, 2025 at 10:44 AM.
Why don't you try to disconnect the sensor and see if your input reading changes? It would allow you to understand if continuity exists in case it changes the error to open circuit or something like that.
O.K. that is a good idea as well. I will try that tonight.
I guess I could pull the left rear wheel speed sensor out of it mounting location as well to see if that results in the same behavior as the right side. I assume if I remove it from it's mounting location away from the mag ring, it should read the same as the right side if the problem on the right side is a bad mag ring that the right wheel speed sensor cannot read.
Why don't you try to disconnect the sensor and see if your input reading changes? It would allow you to understand if continuity exists in case it changes the error to open circuit or something like that.
There is a subtituted value put in place by ABS/ESP modue when and if the sensor wire is disconnected, becareful.
If u can jack up all 4 wheels, remove rear tires/wheel only and do the sensor wiring swap, no need wiring diagram.
Run the car in D while being jacked up. You may need to set to Dyno mode.
The connector is visible under the hairy fender liner.
In green circle
One of them is ABS sensor, one more is brake pad wear out sensor
ABOVE is RIGHT REAR
,
BELOW is LEFT REAR.
One is for level sensor of headlight, in my case. Yours could be for airmatic, if you have such suspension.
One if for ABS/ESP.
There is a subtituted value put in place by ABS/ESP modue when and if the sensor wire is disconnected, becareful.
Yes, that is why I suggested it. He suspects the wiring on the car is bad since the sensor is new. If the signal doesn't change with the sensor disconnected, it would be a good indication his car wiring harness (or module) has an issue.
Ok. So while the code was active the sensor reading was pegged at 407xxmph like the picture. It read this way if the sensor was installed, plugged in but not in the hub or unplugged.
if I cleared the error code speed would read zero like other wheels. Then if I put sensor across new mag ring off to side not installed it would flip to 0.5, 1, 3 mph and then go back to zero when not near ring.
I think this suggests the sensor and wiring works. So points to the mag ring on axle shaft. See video.
strange that once the code was set it was fully pegged and nothing would change the live feed for that sensor.
Last edited by DaveW_396; Jul 7, 2025 at 07:40 PM.
It wont be fun removing the drive shaft to access the magnetic ring.
01. Make sure you torqued all suspension arms at RIDE HEIGHT.
02. The M32 nut is no fun to to torque at 350Nm, as I recalled. The nut is shallow, you need someone to push your socket deep to the nut and you torque it with a 400Nm torque wrench.
Make sure you M32 socket is 12 points and not 6 points. I recalled it is M32. Me brain memory now kinda bad...LOL
Need to grind down the locking ear...I hate that part
.
Thanks everyone for suggestions and help. I’ll let you know how the repair goes. There are a few YouTube videos on the ring repair so I think I have a handle on the scope of work. Certainly looks doable with time.
Ok, I tore everything apart and sure enough the mag ABS ring had delaminated and separated into two pieces.
quite the chore to get the axle out of the hub. I should have removed the e-brake cable since that was limiting my range of motion.
I damaged the new ring when installing, but local dealer had another one. Was very careful with the new one tapping it in place. Reassemble went together without too much trouble.
End result…. problem is solved. Codes are gone and wheel speed sensor readings are normal on all 4 channels.
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