Right Front Speed Sensor again......

[GeoffCapes]

I know this is an issue which appears to be a common Merc Bugbear, however, on the ML yesterday (the missus was driving) she said that the ABS light came on and, to quote "the triangle one with the exclamation mark" light came on, and then the brakes came on.

She turned the engine of re-started without a problem.

Then an hour later the same thing happened. I took the car for a drive and the issue didn't occur.

I called the RAC out to get them to read the codes and the code reader said the following:-

5110 Front right speed sensor
Test wiring/plug connection
Intermittent

5116 Front right speed sensor
Incorrect sensor mounting
Intermittent

Would changing the sensor do the trick or should I get them to change the hub?

I also saw on another thread that someone asked if any work had been done on the brakes recently, but there was no reply. This has had new pads all round recently.
Would that have anything to do with it?

 

[LostKiwi]

Brakes shouldn't make any difference.
It would be worth looking at live values or if you know anyone with an oscilloscope the signal from the sensor. If the signal is dirty the sensor may be bad, the gap to the sensor may be bad or the reluctor may be dirty/corroded.
Might be a long shot but what condition is the brake dust shield on the back of the disk? If it's rotten the rust flakes could be stuck on the sensor masking the signal.

 

[GeoffCapes]

Due to relative small cost I’m getting the ABS (Speed) sensor replaced.
Will see what happens after that.

 

[mioba]

Make sure you get an original and it’s cleaned at the back from where the signal comes.
I fitted an aftermarket to my w220 lasted just over a year. Originals were what - 15 years.

 

[Uncle Benz]

Wheel speed sensors are very common on these. I’ve replaced dozens. They can become very difficult to drive when the fault exists, but they can come and go. 99/100 it is the sensor that’s gone bad.