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Discussion Starter · #1 ·
I am currently having a problem with either my speed sensor, or my wheel bearing (leaning towards the latter).

The symptoms are: ABS, Brake (yellow), 4x4, and TPMS light come on while driving. Using INPA I have found the resulting codes are:

5E43: Wheel speed sensor rear right – dynamic signal loss detected
5E42: Wheel speed sensor rear right – air gap excessive

Monitoring the sensors in real time, I can see the RR jumping higher/lower at random intervals. It is not constant, but happens every so often. I have uploaded the video “as a PDF”, if it is of interest (just rename it). Sometimes I can drive for a while before the lights illuminate.

Although it could be the sensor, to me it seems the sensor is actually reading fine (more than 95% of the time it matches the other wheels). I’ve seen on other BMW forums, that the bearing itself (or the magnetic part of the bearing) can cause this problem.

I’ve heard these sensors rust into the sensor port, so to me it seems most logical to buy both the sensor and the bearing and just replace both. (Sure, normally you might want to swap the sides and see if the problem remains at the RR, but with severe northern rust, I doubt it would be possible without destroying it).

Any thoughts or similar experiences?
 

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Discussion Starter · #3 ·
Update: Fixed

I just want to follow up from original post, as I have corrected the issue. The issue progressively became worse and all 4 warning lights were on 100% of the time.

I replaced the sensor with a Bosch sensor (the original BMW sensor has Bosch stamped on it BTW, and they look identical in every way). The light immediately went out. Nothing looked wrong with the sensor and it was not dirty, but it seems to have failed internally.

I had bought a wheel bearing just in case, however, when I looked through the sensor opening, I saw a tone ring on the axle. The bearing has small little grooves which I thought were for the ABS senor, but I am unsure anymore.

I was worried about the rust, and rightfully so. The hub had rusted and the sensor hole had expanded in size, so getting the old one out was a delicate procedure. Getting the new one in was also very challenging, and I could not get it to seat flush with the hub. Although I was concerned it might be too far to work properly, it was completely fine.
 

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You can clean the hole out to make easyier fitting but you are looking at the reluctor ring through the hole, before you fit the sensor, put a bit of tipex on the end of the sensor, fit it then spin the wheel and check for signs of wear on sensor tip, if it's touching you can place a thin crush washer under the the sensor bolt to lift it away from the reluctor ring, if you lift it too much sensor can't read it and you will get an air gap fault, I did that and got away with it for quite sometime but I had to change the reluctor ring eventually and never had a problem since.
 

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Discussion Starter · #5 ·
You can clean the hole out to make easyier fitting but you are looking at the reluctor ring through the hole, before you fit the sensor, put a bit of tipex on the end of the sensor, fit it then spin the wheel and check for signs of wear on sensor tip, if it's touching you can place a thin crush washer under the the sensor bolt to lift it away from the reluctor ring, if you lift it too much sensor can't read it and you will get an air gap fault, I did that and got away with it for quite sometime but I had to change the reluctor ring eventually and never had a problem since.
Good points. I had very minimal wear (scrapping on the sensor tip). The new one is sitting further out due to the rust (which is severe, being from an extremely high salt area up north). Hopefully this will keep the car happy for a while. When I saw the reluctor ring, I think I saw a crack in it so we will see.
 

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I had replaced rear right sensor in past but did not resolve my issue. So did u replaced sensor, reluctor ring and wheel bearing to fix your issue ? Or just sensor.
I did use Bosch sensor, but still gives
5E42 code for rear right speed sensor

Regards,




Regar
 
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