Weird Judder/jerk when driving w166 ml350 bluetec

[kang]

Hello all,

I've got a 2012 ml350 cdi with 73k. Full MB service history etc and has been trouble free so far. Last month I replaced all speed sensors and a single hub where the magnetic sensor had corroded. A few days ago the engine light came on for the NOx sensor with the following codes:
P2201
P229f
P22fa

No liss of power etc or adblue warning messages and I'll get round to changing the sensor. I've noticed that the car when driving on the motorway at 80+ or under acceleration there is a noticeable jerk/judder which happens for a split second but you feel it as if the brakes were tapped quickly. Nothing logged on errors etc and monitoring speed sensors there is no drop in speed. I'm puzzled what could cause this. It happens randomly and only once has it caught me while I had kickdown enabled, it's worrying but the car continues on normally.

I've got xentry and the only codes showing are for the SCR system as mentioned above.

Has anyone come across this or can explain this?

 

[AMGeed]

Has the ATF ever been changed?
It could be £250 well spent if its not been done before.

 

[kang]

Has the ATF ever been changed?
It could be £250 well spent if its not been done before.

ATF was changed 2 years ago and it's not really due anytime soon. I thought of that but gearbox is smooth and changes are seamless

 

[ajlsl600]

Hello all,

I've got a 2012 ml350 cdi with 73k. Full MB service history etc and has been trouble free so far. Last month I replaced all speed sensors and a single hub where the magnetic sensor had corroded. A few days ago the engine light came on for the NOx sensor with the following codes:
P2201
P229f
P22fa

No liss of power etc or adblue warning messages and I'll get round to changing the sensor. I've noticed that the car when driving on the motorway at 80+ or under acceleration there is a noticeable jerk/judder which happens for a split second but you feel it as if the brakes were tapped quickly. Nothing logged on errors etc and monitoring speed sensors there is no drop in speed. I'm puzzled what could cause this. It happens randomly and only once has it caught me while I had kickdown enabled, it's worrying but the car continues on normally.

I've got xentry and the only codes showing are for the SCR system as mentioned above.

Has anyone come across this or can explain this?

Had exactly that three week ago and abs, stability lights and tyre press warning icarsoft came up with f/r wheel speed sensor second time in 3 month, different sensor. If I cleared it it wud go. Then car would jerk a bit at times then yellow abs and stability along with error code for f/R/wud come back on then jerking disappeared until I cleared again then same issue. Nothing since sensor changed I think cos sensor playing up its either not sure which gear to be in, or it's applying a brake because of data error? Not certain, but no issues on that matter since change. Incidentally on previous sensor right rear there was no jerking involved.
Why it cant average working sensors when one fails instead of all this bollocks I don't understand like most modern car systems, it just makes the cars unreliable and stressful. Maybe that's makers idea?
Mine is ml250 blueshxte w166

 

[kang]

Had exactly that three week ago and abs, stability lights and tyre press warning icarsoft came up with f/r wheel speed sensor second time in 3 month, different sensor. If I cleared it it wud go. Then car would jerk a bit at times then yellow abs and stability along with error code for f/R/wud come back on then jerking disappeared until I cleared again then same issue. Nothing since sensor changed I think cos sensor playing up its either not sure which gear to be in, or it's applying a brake because of data error? Not certain, but no issues on that matter since change. Incidentally on previous sensor right rear there was no jerking involved.
Why it cant average working sensors when one fails instead of all this bollocks I don't understand like most modern car systems, it just makes the cars unreliable and stressful. Maybe that's makers idea?
Mine is ml250 blueshxte w166

That's interesting and I thought about that aswell. I could have a faulty abs sensor but it's happening so intermittent that instead of getting the lights etc, it confuses the car for a split second, clears and then continues normally. I'll see if I can pick up a cheap sensor and see how that goes. It might take me some time to sort out but I'll feed back once I get to that stage.

It definitely feels like when esp cuts in when you lose traction

 

[ajlsl600]

Get on scanner find out which if any come up faulty. Be prepared for wiring issue to from sensor.

 

[kang]

Hello all,

I've got a new symptom now. Started the car and it didn't feel like it had power etc. When I pushed it a bit harder all the power was there etc. A few moments later the car was struggling to get to 1500rpms and juddering/shaking. All this was done locally at under 20mph.When I forced it, all the power was there. It's very similar to an issue I had a while ago with a 320 cdi who had a faulty egr. I plugged the car, scanned it and just the nox sensor codes came in. Nothing else came up. I did a quick test drive looking at the speed sensors and they're all within tolerance but the car was still doing it's juddering etc

 

[ajlsl600]

And no further faults logged?

 

[kang]

And no further faults logged?

No codes at all, I've rescanned using 2 different machines and the same codes for the NOx sensor keep appearing
P20ee
P2201
P22fa
P229f

When I clear the codes the car runs fine and then if I drive say 50miles or so, the codes reappear and you can tell something has changed. I think the nox sensor(s) are causing this. I've got the car booked with Mercedes in the next few weeks and I really hope they change the sensors FOC aka gesture of goodwill seen as the car had the full MB history

 

[ajlsl600]

Hope so good luck.my speed sensors were in specc to when I looked at live date

 

[kang]

Update:
Both Nox sensors are Kaput, and the work will cost £1.5k to put right. No gesture of goodwill available, and both dealer and Merc HQ are not interested. I've booked for the work to be done and the next slot is 3 weeks away.
Sensors cost £900+vat
The rest is labour and software updates

BTW, the adblue message showed up after approx 300 miles with the above warnings, and It gave me 750 miles until engine no start. However, the 750 miles was very vague, and a 2-mile journey dropped the figure by 8 miles.

 

[kang]

Another update.

The weird judder at different speeds csme back and got worse with time but no codes were being logged and no lights were lit. It got to the point where the car was jerking over bumps small and large as you went over them. The gearbox started having a mind of its own and not being butter smooth as it normally is. On 2 ocassion it felt like the steering wheel was not connected to the wheels for a brief moment.

Coincidentally, the rear brake discs and pads were changed and the ABS light came on and all ascociated systems flagged for faults.The issue was traced to a faulty speed sensor which was changed a few months ago, but, swapping it to the different side it was working. The garage took a pun and changed the ABS wiring from the sensor to as high up as they could see (about 50cm) and all issues disappeared.

The wire they cut out was checked for resistance and it wasn't consistent and kept flickering between values. They assumed the wire was stretched or had corroded even though it looked good. I've put some serious miles on the car since then and not a single fault, even on our pot hole ridden roads.

I hope this helps someone out there.