ESP, ABS, Run Flat, Cruise Control randomly disabling themselves part way through journeys 2009 E350 CDI Coupe

[malphadour]

Hello MB experts.

2009 E350 CDI Coupe

As per the title, recent issue of all the electronic assistance aids popping up with disabled messages. Start the car the next day and works fine. Doesn't come up during local journeys, but tends to come up on longer runs.

My battery is fairly new - approx 2 years old - so my first guess is failing alternator. Does this sound like the most likely candidate? One of the things that has always happened is my little 12v blue tooth adapter always gives me a warning to check the car battery when I switch on the ignition - it has done this for 4 or 5 years with old and new battery - lazily I put it down to the adapter being a bit sensitive- however the electrics in general have given me no issues until last week.

One other symptom, and I don't think I am imagining this, is there is a bit of a different engine tone that is noticeable when driving, but can't be heard when stationary which again makes me think alternator dying.

Anyway - over to you peeps who know way more than me - thanks in advance for any replies.

 

[Jobsworth]

Sounds to me like you have a failing wheel speed sensor or reluctor ring.

 

[rf065]

My SLC used to do this after 2-3 hours driving, always fine on shorter drives, wheel speed sensor.

 

[malphadour]

Ok - never even thought of this and it does seem to match. I assume there are 4 of these - so how do I know which one is gone - can a garage plug in and get that info?

 

[Jobsworth]

Yes, a code scan is the best way