L322 ABS Re-learn Procedure? Is there such a thing?

The back story to my question here is that I had a CV joint failure and although the replacement was nice and simple I've been getting sporadic ABS faults since. Specifically, this one:

• C0031-25 (E8) Front left wheel speed sensor - General signal failure - signal shape/waveform failure
  ( on 19-03-2025 12:36:36 at 93157 mi )

I wanted to remove the ABS sensor when I was changing the air spring as it loops around the shock leg and I didn't want to damage it but of course, it was seized in there so I bravely decided to leave it alone at the time. After about 15-20 miles on the new CV, I got the above error and decided to replace the sensor. Did that, still have the same error popping up randomly so I'm fairly sure the issue can be attributed to the new CV joint reluctor ring. Question is, why is it not doing it all of the time?

I took it for a drive last night and got maybe 1/4 mile in a straight line and had this issue pop up. Reset everything and then drove about 8 miles with no issues at all. Of course, the latter drive was with GapIID connected and logging data from the wheel speed sensors so it wasn't going to fail then was it?

Interestingly (to me anyway) the logging appears to record the speed of the driveshaft passing rather than the speed of the car, either that or I have a land speed record setting L322 that can achieve 200+MPH in 1/8th mile!

Anybody had the same or have any thoughts as to why I'm getting this issue? I'll be gutted if I've introduced a sporadic fault to my otherwise excellent car.

the abs ecu either sees and responds to a valid signal, or not. theres nothing to learn

Did you push the sensor fully home?

That's what I thought, on, off, on, off.... Again, this doesn't seem to make sense as it sometimes doesn't work, if it wasn't getting a signal it would never work. it's not caused when cornering for example, it's happened 4 times, twice in a straight line and twice on long bends. I can't work out a pattern to it.

This was the bit that confused me: "signal shape/waveform failure". I wondered if it could be difference in the hole sizes on the ring but surely it would need equal parts of material there and not there to give an accurate depiction of movement wouldn't it? My only thought on the re-learn was triggered by thoughts of Steering Angle Sensor and ABS issues

I made sure it was all clean in there before the driveshaft went back in and when I replaced the sensor I could see the reluctor was properly centred on the hole for the sensor.

I've highlighted it to Maltings where I bought the CV joint just in case I need to return it as I can't see what else could be causing the issue.

Datatek said:

Did you push the sensor fully home?

Click to expand...

Yes and made sure to clean the mating face so that it was properly seated but this started before I'd removed the old sensor so that replacement has made no difference at all.

Silly question, you did check the connector was free of corrosion?

Yup, after my day of off-roading a couple of weeks back the box was full of mud but the connector seal had done its job and everything was spotless inside. I'm convinced this is the CV joint as I've never ha a single issue with this until I replaced it, Common denominator and all that, I've got to get some metal blades for my recip saw at lunchtime today (wishbone replacements on the good lady's D4 this weekend) so I'll test it again on the way to Toolstation. If it keeps up I'll buy another CV joint and replace it again, can't put up with these errors, didn't have them last week, no need to live with it as so many do.