Ok so this afternoon I had some time to kill and the weather was great, so jacked up the car both ends to check out both speed sensors. Under the M3 the junction box the connector sits in is behind two panels that stop water splashing up and keep the underside flat. These are somewhat annoying to remove...
Anyway, I got both sensors out and they had no signs or damage and I'd say they looked relatively recent, certainly not original items so someone has changed them in previous ownership. They both has a layer of dust/rust from the steel frame they sit in, so I cleaned them both up, as well as the frame. I'm guessing the rust layer acted like iron filings causing erratic readings hence the error codes. I also looked through the hole to the reluctor rings and they both looks nice and silver, no corrosion signs on them. So I have no idea what the scraping noise was from the rear right wheel which I mentioned above. Symptoms pointed to the ring scraping against the sensor, but this appears to not be the case.
Put the sensors back in and fired up Carly to clear the codes. Too knackered to go for a drive to test so will do that mid-week perhaps. If the errors come back the investigation continues.
For reference, these were the error codes:
Both codes refer to an ABS sensor issue^
Apologies for jumping the gun and thinking it was the ring(s)! All signs pointed to them!
It's been quite fun driving without DSC these past few weeks. By fun I mean no different at all