2013 ML350 BT, close to 270 000 km. Had the AEM done 10 000 km ago.

In the past week, multiple issues appeared out of the blue.

First, I got a random CEL with no other symptoms. I didn't have time to pull my scanner, so I just ignored it for a day or two. Then it went away after I filled up the fuel tank. I figured I got a bad batch of fuel?

Then, the next day, I'm cruising in nearby country roads with the cruise control on and when I hit a road bump/pothole (wasn't a big one), my SUV jerked and cruise control became inoperative. It was like a rpm/transmission jerk. On my way back home, my dash lit up like a xmas tree. ABS/Traction control, electric brake lights all came on, along with a CEL. Steering wheel feels stiffer than before. I get a pulsating brake pedal when I apply the brakes. Same feeling as when you try to brake on a slippery surface. I figured an ABS wheel sensor crapped out?

Back home, I pulled my scanner and got a wall text of codes...

Car Scanner ELM OBD2DTC reportSelected brand: Mercedes-BenzVIN: 4JGDA2EB4DA231578
​​​​​​
============1==============C003ARaw code: 403AECU: Engine control unitStatus: ConfirmedRight Rear Wheel Speed Sensor

============2==============P20E8Raw code: 20E8ECU: 7ECStatus: ConfirmedReductant pressure - pressure too low

============3==============U0416Raw code: C416ECU: 7ECStatus: ConfirmedInvalid data received - vehicle dynamics control module

============4==============P1A3B(00)Raw code: 1A3B00ECU: Engine control unitStatus: Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested

============5==============P20E8(23)Raw code: 20E823ECU: 7ECStatus: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clearReductant pressure - pressure too low

============6==============U0416(29)Raw code: C41629ECU: 7ECStatus: Pending, Confirmed, Test failed since last DTC clear, Warning indicator requestedInvalid data received - vehicle dynamics control module

============7==============P20E8(21)Raw code: 20E821ECU: 7ECStatus: Test failed, Test failed (current drive cycle), Pending, Confirmed, Test failed since last DTC clearReductant pressure - pressure too low

============8==============P1606(00)Raw code: 160600ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clear, Test not completed during this operation cycleECM Control Relay O/P Circuit Malfunction

============9==============P161F(00)Raw code: 161F00ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clear

============10==============P1623(00)Raw code: 162300ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clearImmobilizer Code Word/ID Number Write FailureImmobilizer Code Word / ID Number Write Failure

============11==============P1606(00)Raw code: 160600ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clear, Test not completed during this operation cycleECM Control Relay O/P Circuit Malfunction

============12==============P161F(00)Raw code: 161F00ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clear

============13==============P1623(00)Raw code: 162300ECU: Engine control unit[Archive (inactive)]Status: Test failed since last DTC clearImmobilizer Code Word/ID Number Write FailureImmobilizer Code Word / ID Number Write Failure

============14==============P1A3B(00)Raw code: 1A3B00ECU: Engine control unitStatus: Pending, Confirmed, Test failed since last DTC clear, Warning indicator requested

============15==============U140CRaw code: D40CECU: Transmission control unit[Archive (inactive)]Status: Validated and stored in non volatile memory

*********

​​​Sure enough, it seems the rear passenger side wheel ABS sensor is shot, so I'll pull it apart and clean it for debris to see if it fixes the problem... If not, I'll buy a new sensor.

The codes regarding the Adblue system (P20E) are odd because they changed everything during the AEM procedure. They told me I had a code for a malfunctioning def pump and the leveling sensor inside the def tank so they changed them... So I guess my def pump died already? I'll bring it to the dealer for this issue since this should fall under the AEM warranty...

This is not all... I noticed a strong burning smell coming from the rear of the SUV when I parked it yesterday. There's also an oil leak (noticed oil on the garage floor). Not sure if it's the infamous oil cooler seals... I just hope it's not a transmission leak and the transmission is going out! I've read on the forums that some said it might be the throttle body???

I'll be back home in 2 weeks to start checking everything. The timing is horrible since I'm going to Orlando/Disney with my daughter next week for the March break.

My mechanical skills/knowledge is limited. Can a bad wheel ABS sensor cause the jerking??? Or is this a seperate issue?

Regarding maintenance, I change the fuel filter every 30 000 km myself and bring it to an indy shop for a transmission oil/filter change (not flush) every 100 000 km. Both were done at 250 000 km (so 20 000 km ago). But the original and auxiliary batteries are original (10 years old).

Thank you guys.

 

Quick update. Fixed the issue after changing the ABS wheel speed sensor. The check engine light code indicated the rear right wheel sensor. I removed it and cleaned it but still got the CEL and issue. I ordered a new sensor from Rockauto for 80$, changed it and voila! Cleared the CEL and everything is good now. No more problems.

 

Update.

Well the issue seems to come back sporadically. No check engine lights. When I hit uneven road bump and the suspension goes down, my RPM will become erratic and this jerking/pull appears. Sometimes, I still get the 4 dashboard lights (amber parking, ABS, and two ETC). Cruise control goes inoperative. Shutting off the car and restarting the engine gets rid of the problem until the next road bump. Changing the ABS wheel speed sensor fixed the check engine light and the problem appears less often than before.

Potential culprits? Batteries are 10 years old (both main and aux), low transmission fluid (had the transmission fluid changed 20 000 km ago along with the filter and new gasket/pan bolts), maybe the passenger side rear bearing is causing the issue?

 

Update.

Check engine light popped today. Same code as before. Rear right wheel sensor. So the sensor is either not good (new but aftermarket) or it's the wheel bearing. I ordered a new Timken wheel bearing via Rockauto and I'll change it myself. Hopefully, this will fix the issue...

 

So a couple of days ago, I took the right rear wheel off and wiggled with the sensor. Made sure everything was snug. Put the wheel back on and then proceeded to change my main battery (under the passenger seat). I was still on my original battery (10 year sold). I then started to take apart the trunk to reach the aux battery and for some reason, I learned that there's two different aux battery sizes. When I ordered both batteries through Costco, they sent me the "big" aux battery (size of a motocrycle battery). I noticed that mine is the "smaller" aux battery (about the size of a pack of cigarettes). I ordered the correct aux battery through my local Mercedes dealership and I'll be returning the other aux battery to Costco.

Knock on wood, the ABS problem hasn't come back. Was it the battery or the sensor connection that was the culprit? Can't really tell for sure.

I'll just return the wheel bearing to get a refund. I'll update if the problem comes back.

 

Replacing the old batteries is a good choice. 10 years is about all you will get outta quality batteries on the W166, and there are so many sensitive electronics on these, inconsistent, or lower voltage from old batteries can create all sorts of gremlins. Check under spare tire, all of the way down to the body metal to make sure you don't have water in there getting into any electronics (current active recall on these). Sorta sounds like the yaw sensor is giving your stability control system a bad input. I believe it sits under left side driver's seat, mounted to floor.

 

I'll 2nd Leetom on the good choice of replacing the batteries. I've had some odd issues pop up just prior to changing my batteries and the issues all cleared, was around the 10 year mark as well.

Hope your issues are all resolved.

 

+3 on the batteries. Getting all of those issues / codes at once are indicative of a voltage drop to the various electronic modules in the car.

 

I will add one more : clean ground connections, in particular those exposed to the elements: engine to chassis, communication related grounds (foot wells driver and passenger sides), and any ground you find.

You will find a oxide/rust (or even paint/primer) layer between the post and the connector: brush it off, use deoxite, and tight properly.

There are other faults related to mechanical connection between boards instead of soldered connections that trigger --> miscommunication between the modules. For example, if the symptom occurs and it goes away by turning the car off, shut the computers down (double click on the keyfob), and restarting the car on you can bet there is a software glitch likely trigger by a "bump on the road", or "knocking on the module too hard when shifting manually, or changing reverse/forward", or "stomping on the carpet".

 

sorry I don't understand, but did you solve the vibration?

 

Well I spoke too soon. Symptoms are back... Same thing as before. I'm trying to find the abs tone rings for the w166 models and I can't find any... I called my local Mercedes dealership and the parts guy is saying he can't see them in his parts catalogue...

Do I have to change the whole darn CV axle???

 

Here is are the parts listed in the EPC


and you are interested in (15), I guess

 

Thanks! So, pardon my ignorance I'm no mechanic, it seems that I need part 15?

https://partszone.ae/en/parts/MERCEDES-BENZ/A1663507000

Sure looks like it.

 

(130) is a rubber boot to hold the grease in the back of (15). and the rings are to hold/seal the grease on the shaft and housing side. I doubt those rings are ABS speed sensors.

The ABS ring (reluctor I guess is the name) must be able to fit into the steering knuckle where the sensor (the one with the cable) can sense its motion

It seems it is built-in as part of the housing of the CV joint. Or it is not even there, but part of the bearing. You must separate the steering knuckle and see the current state of it.

NOTE: I have never done this kind of work on the W166, so take my comments with a grain of salt.



From another thread (https://mbworld.org/forums/gl-class-...ml#post6525286) Definitely in the bearing. so NO need to get the drive axle, just a new bearing. Just be careful of the orientation when installing the bearing
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Read updated post above..

 

So quick update. I still had problems after switching batteries and the abs sensor. I decided to change the wheel bearing and this fixed the problem. The bearing was extremely rusted and I guess the magnetism strip was too rusty and simply not magnetic anymore.