My 2013 Glk350 4Matic (55k miles) had the right front speed sensor die. This caused your instrument panel to light up in ways you have never seen because it kicks out cruise, traction control, ABS, Check Engine, and it goes into limp mode. Kinda a WTF moment.

Got it out of limp mode to get home and I used my OBD scan tool and got the following codes. I was impressed

Global

C0034 Right Front Wheel Speed Sensor

P061A Internal Control Module Torque Performance


ABS

600100

727100

726600

511700


Mercedes OEM Enhanced

062C00

403408

D40A


Replace process is quite easy and only requites a few tools (Socket set, ratchet, extension, small screw driver flat blade) and I also used Electrical contact cleaner, silicone spray, Blaster Penetrant, small needle nose and wire brush.



1. Remove the Wheel

2. The sensor is mounted inboard of the disc brakes on the front side. I will have a cable running through a number of looms to disappear beneath the plastic inner fender liner. It will meet up with the cable coming off the back side of the disc brake assembly under the liner. I applied some Blaster to the small bolt holding the sensor end in.

4. Remove the back half of the liner. There are a few fasteners under the chassis.

5. Remove the nut holding the sensor and remove the rest of the cable from the inner fender plug (disengage the wire retainer)

6. Reasssemble in reverse

7. I used the contact cleaner on both leads and plugs; I used silicone to help put the cable back in the looms and retainers;;I used Locktite on the retaining bolt. I also clean the threads on all the wheel lugs.

I used the scan tool to reset all but the permanent codes. It took two 20 mile drives for the computer to reset and delete the permanent codes

 

Great tip. Same symptoms and problem on my S550 recently.
Thanks for posting.

 

Your very welcome. I am glad that the info was helpful.

 

My Left Front Speed Sensor just died and exhibited the same symptoms and codes (except for the code left vs right) as I indicated above. This is getting annoying and specifically Limp Mode. Maybe I should have replaced both when one goes out?

 

Some times the problem is not the sensor itself, rather dirt on the "tone wheel" that the sensor senses. Also, depending on how it is mounted, rust may push the sensor away from the wheel enough to make the signal unstable.

 

Thanks for the input John.

I cannot speak to the left but for the right one I thought about dirt and even metal fragments on that or the sensor head. I found no dirt or metal on the sensor head and no damage to the plastic cover encapsulating the sensor as if it was abraded by dirt or scraping against anything. The mount and bolt on the right side had no rust and very little dirt (I hit the wheels and wheel wells with a pressure washer). I hit all the contacts (new and old) with CRC electrical contact cleaner before reassembly to be sure any corrosion/dirt that may effected the signal was removed.

The new one on the right has been in two months so I guess we will see. If I see anything of substance I on the left one I will post it.

 

I just had the same code pop up on our X166 GL450. I wasn't moving when it came up.

Thanks for posting.

 

Your welcome. I imagine you found this failure as puzzling and frustrating as I did.

 

Indeed. I stopped for our security gate and the screen for the GPS went black and the lights in the dash lit up. Only code is the P016A, I’ve ordered both wheel sensors and hoping it fixes the issue. It did rain last night and our GL stays outside so it’s in the weather 24/7.

 

I replaced the left sensor and did note a small amount of black dust on the sensor. The used the same processes I used for the right side replacement except I did use a fitting I attached to my air blow gun and blew some low pressure (~10 PSI) air into the sensor mounting hole.

 

The only temporary issue you might see is the onboard computer may take a few miles to reset (i.e., all the warning lights) even though you erase the DTC codes with your scan tool.

 

I just wanted to update the thread. My battery was draining and causing issues which turned out to be a torn boot around the drivers side windshield wiper and the water was being dumped into the area near the abs module and a bundle of wires that were sitting in water. There was old leaves that clogged the drain holes so I ended up patching the boot, pulling the wiring loom up out of water and tie strapping it so it couldn’t get wet. No issues since. It had rained for a few days the last time this happened.