ABS fault - rear left wheel sensor

**leighmagill** · 01-01-2011,05:06 PM

Hi, I have a 1998 A4 1.9 tdi with 86,000 miles. When I bought it the ABS light was on so I bought the VAG-COM lead and downloaded the VCDS-lite software.
The scan showed the rear left wheel sensor. I have just replaced the rear left wheel sensor and cleared the codes. Went for a test drive and the abs light came on again. Same fault code, rear left wheel sensor, cleared the codes and went for another test drive and it came on again

Any ideas?

Thanks in advance, Leigh

**Crasher** · 01-01-2011,05:31 PM

Where did the sensor come from?

**leighmagill** · 02-01-2011,02:12 PM

Ebay, not a genuine part, the same thought has crossed my mind, false economy. I might take the rear disc off next and check the condition of the reluctor ring ( there was a lot of debris on the old sensor ) then maybe try a genuine audi sensor?

Thanks, Leigh

**Crasher** · 02-01-2011,02:22 PM

You can watch the sensors output in Measuring Blocks, jack the car up, put VAG-COM into measuring Blocks and spin the wheel. Check the clearance of the sensor to the ring I have seen the rings completely rust away.

**JASEA4** · 02-01-2011,02:51 PM

mate find my post re abs traction light , may be of use to you , i have been through all those issues and now all sorted and happy

https://www.vwaudiforum.co.uk/forum/s...d.php?t=108761

**leighmagill** · 20-01-2011,05:08 PM

Hi, finally got round to looking further into my ABS problem. I'd bought an ABS reluctor ring thinking that the rear left must be rusted/damaged as I'd replaced the sensor and still had the same fault showing.
Well, took the rear left disc off only to discover that there was no reluctor ring fitted

. The discs and pads had been replaced by the previous owner last year. So reset the fault codes, drove off, and you guessed it. The ABS light came on again. Plugged in the VAG-COM and this time it showed the fault was the rear right ABS sensor. Drove straight to Audi and picked up another reluctor ring, as I suspected the ring was missing from the right as well. All back together, no lights, ABS now working, sorted

. Find it strange that the VAG-COM initially only showed a fault with the rear left when there was a fault with both sides?

Cheers, Leigh

**JASEA4** · 20-01-2011,07:14 PM

nice one mate hope my thread helped you , its funny because mine was showing n/r replaced it all , eventually vag come decided it was sorted but when light came straight back on through the fault over to the o/s rear thats why i did the lot equal both sides and im all sorted , very strange you had similar issue but supprised your fault didnt show earlier with no ring at all , never mind your fixed now

i bought my rings from gsf £11 each how much where they from audi???

**MarkTM** · 09-04-2015,04:56 PM

Where did you guys buy your ABS rings from? No idea which one to buy for my 07 A6 as Ebay isn't being helpful.

In th case of my front Audi dealer spoke to Master Tech who advised it's built into the wheel hub and magnetic?

**Crasher** · 09-04-2015,05:31 PM

Yes it is a magnetic ring on the back of the wheel bearing assembly, you can't buy it separately.

**MarkTM** · 10-04-2015,08:12 AM

OK, so most aftermarket ones will have it fitted if specific to my year/model, such as this one:

AUDI A4 AUDI A6 C6 AUDI A8 FRONT WHEEL BEARING HUB KIT NEW | eBay

Natch will ask the seller first

I believe in my case it's the wiring loom (which has clearly been repaired by the previous owner) and new from Audi these are £58.86 inc (part no 4F0972252)

So may try a new speed sensor first as the cheapest option.