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My 2014 C300 has an erratic abs speed sensors, I think??
So early this year after a normal drive the TCS, ABS & TCS OFF lights all came on the dash as well as a message in the center info display stating the systems were inoperative and to refer to my owner's manual. So I did online research on common issues that could trigger this, and most of my symptoms pointed to a failing/failed abs wheel speed sensors. Hesitation on takeoff, wheel spin on takeoff etc etc. So my natural instinct was to refer to a local mechanic to get this job done. And they then confirmed my theory was right and that the abs sensor has gone bad. So lots of money spent and "replaced" parts later. It was fine for a while, not a single light on the dash whatsoever until a couple weeks later. It came on while driving right after i felt the car jolt. This was new, not only did the systems not work but when the car was first started/driven there would be a jolt during your initial takeoff. And sometimes even the check engine light itself would come on!!! This car has already had a history of problems that I won't mention as they aren't relevant/already fixed. But this has been a lingering and dangerous problem. And if the car has sat in the cold for a while sometimes the systems will reengage temporarily until driven for about 5 minutes or so, wtf is wrong with my car? 2014 Mercedes C300 4Matic Sport w/ sub 80k miles
What parts did they replace? and you probably didn't get told what wheel it was. But lets start with you'll need to identify which wheel it is with a Mercedes specific scanner off amazon they are like 150$
second there are two parts to each wheel sensor the electrical pick up or the wheel speed sensor and the magnetic ring that give electric pulses for the sensor to pick up. I'm guessing they only replace the sensors and the magnetic ring or rings are bad. Our cars have a habit of the rear ring rotting off the rear CV axle and they need to be replaced sometimes.
Basically figure out the wheel then if its got a new sensor then its probably the magnetic ring.
I'm in the same exact boat as you. Same everything!
I was able to change the left rear wheel speed sensor but when doing this, I noticed that my rear subframe had failed and it's been at Mercedes until yesterday...took the dealer 4wks to complete my subframe; it was under the 300k mile warranty so job was free but took forever.
When they brought me back the car last night, all the lights were lit. Going to get the right rear sensor swapped and hope that's it. I'll report back to this post when/if I figure it out.
Also, are the wheel speed sensors separate from the ABS sensor mentioned?
I'm in the same exact boat as you. Same everything!
I was able to change the left rear wheel speed sensor but when doing this, I noticed that my rear subframe had failed and it's been at Mercedes until yesterday...took the dealer 4wks to complete my subframe; it was under the 300k mile warranty so job was free but took forever.
When they brought me back the car last night, all the lights were lit. Going to get the right rear sensor swapped and hope that's it. I'll report back to this post when/if I figure it out.
Also, are the wheel speed sensors separate from the ABS sensor mentioned?
I changed both rear sensors and still had the traction control and abs lights. It is also locking up my front left caliper. I was able to clear the codes but it is still locking up my front left caliper with traction control lights. ugh....
Last edited by oldghost; Nov 15, 2025 at 05:06 PM.
I changed both rear sensors and still had the traction control and abs lights. It is also locking up my front left caliper. I was able to clear the codes but it is still locking up my front left caliper with traction control lights. ugh....
Rear speed sensors replacement won't do anything with the front. Inspect both front sensors. My front right sensor just got loose 😠
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My 2014 C300 has an erratic abs speed sensors, I think??
