There are no magnets in the ring.

 

The sensor has a magnet and a hall sensor, when the "teeth" of the castellation pass the magnet it reduces the magnetic field acting on the hall sensor changing its output state. Failure mode is the sintered magnet fracturing from impact, in my case clipping a kerb.

 

I have no idea why you are advocating Taff B to undertake the very difficult and expensive job of replacing the wheel bearing and trigger ring without knowing it is faulty when the ABS sensor can be replaced for a few pounds in a few minutes without even jacking up the vehicle. If the fault remains then for sure the trigger ring is likely to be the problem but any build up of rust can be cleaned out very easily while the sensor is removed.

Magnets may well be there.

Many recent (last 25 years approx) VW group cars use this system, with alternating magnetic poles in a ring integrated into the inner face of the wheel bearing assembly;

Speed Sensors & Rings: A Complete Guide - ACTRONICS LTD

9 hours ago, J.R. said:

There are no magnets in the ring.

 

The sensor has a magnet and a hall sensor, when the "teeth" of the castellation pass the magnet it reduces the magnetic field acting on the hall sensor changing its output state. Failure mode is the sintered magnet fracturing from impact, in my case clipping a kerb.

 

I have no idea why you are advocating Taff B to undertake the very difficult and expensive job of replacing the wheel bearing and trigger ring without knowing it is faulty when the ABS sensor can be replaced for a few pounds in a few minutes without even jacking up the vehicle. If the fault remains then for sure the trigger ring is likely to be the problem but any build up of rust can be cleaned out very easily while the sensor is removed.

Each to his own opinion, Taff asked for opinions as to where he should start first, I’m just saying, given the circumstances, my money is on the ABS system.

As for changing the sensor in a ‘few minutes’, hmmm, tell that to the workshop 😁.

Have you ever changed one that came out cleanly, they invariably snap off at the connector end?
As for there being magnets in the ‘exciter’ ring - I’m fairly sure there is on my VW Golf hub, however, I’m not putting all my money on the nose, the Superb may be different.

Thanks for the informations, every day is a learning day and may it continue to be so.

 

My "opinion" not given with such unwaving certainty would be to suspect the sensor, if the person does not have access to VCDS to confirm its failure then my suggestion is to replace that first as it is cheap and easy, or bloomin expensive if you pay a dealer to do so.

 

1 hour ago, Berisford said:

Have you ever changed one that came out cleanly, they invariably snap off at the connector end?

 

They have all been rusted in place some very much so but I am patient and persistent and as long as I keep my hand in have a good feel and ability to keep just below the material yield point.

 

5 minutes was enough for me, within a minute I would know if it was a lost cause and I would have to drill it out, swapping out the wrong hand sensor that I had temporarily fitted (bodged) with the correct one took 45 seconds.

Edited 24 August, 20241 yr by J.R.

Battery purchased from Halfords website and fitted at one of their depots. Technician cleared all faults and told bms about battery. Strangely enough when I started the car to go there, it told me that the bonnet was open, it wasn't, I got out to check.

Will give it a few weeks and see if anything comes back up.

Got a good deal on battery using Halfords trade card, well worth it if you qualify for one.

21 hours ago, taff_b said:

Battery purchased from Halfords website and fitted at one of their depots. Technician cleared all faults and told bms about battery. Strangely enough when I started the car to go there, it told me that the bonnet was open, it wasn't, I got out to check.

Will give it a few weeks and see if anything comes back up.

Got a good deal on battery using Halfords trade card, well worth it if you qualify for one.

Pleased you got it fixed for nominal money - my bet on the ABS exciter was wrong - I’ll get my coat!

Berisford

 

Don't be too hasty in getting your coat, I have not done the miles yet to see if its fixed it. Might have to wait until I do a long journey to know for sure, next one due is back to Solihull at end of September. I will update on any changes.

Not used the Superb much over the last couple of weeks, so no update. However, I did a trip to Carlisle from St Andrews and back last Thursday, so about 360 miles all in. No indication of any problems, so it looks like the new battery has fixed it.

 

Good to know, as I would never have thought of it, as the battery was starting the car with no bother at all, and nothing picked up on its annual service.

 

Thanks to all who contributed to this thread, and came up with the solution.