Repeated intermittent ABS light issues
 

Been getting repeated but intermittent ABS light issues, with accompanying ECP error over the last few weeks.

Pretty much in each case preceded by a bump in the road and a triggering of the ABS under braking.

Always self clears after teh ignition is cycled .

I'm guessing ABS sensor though who knows which one. Anything else likely to be the cause?

Pads and disks are pretty new and loads of wear left but generally I'm also notice a roughness under heavy braking if that possibly related??

Very likely a sensor if it clears itself. It could be failing or it could simply be dirty with rust particles stuck on the end so it is reducing the sensitivity. With these sort of faults you need to check the codes before cycling the ignition to catch whichever one it is, then you can dig deeper in to that sensor.

thanks MJ are the 4 sensors all the same part number or are they different

Front (alloy upright) 4D0927803D
Front (steel upright) 4D0927803E
Rear 4D0927807B

If its the fronts you can use this guide:

http://forum.a8parts.co.uk/showthread.php?t=16839

To save yourself ~£350

thanks for that hadn't realised they were quite so expensive

thanks Mikki

would you know what the difference is between those for the steel and ali uprights other than part number?

having had a look yesterday with the intention of giving them, a clean in the first instance.

it seems they likely have never been removed in 20 years and whilst I could get teh retaining bolt out the sensor remains steadfastly stuck in place.

Any tips for removal without destruction short of dropping the drive shaft and pushing from inside the hub?

I did my front ones years ago, and thankfully only one was stuck. I just sprayed the living daylights out of it with WD40 over a few days, whilst trying to wiggle it left and right and in and out. From memory, once there was a smallish gap, I used a fine screwdriver to gentle prise around it, keeping it as straight as possible. Still drenched it as I went, but eventually came out. Then gave the housing a good cleaning with some fine emery paper. Didn't need to go near the rear ones, but did them anyway as a form of precaution.

Dropping the shaft and making a tool to push it out is the only way, but still all that effort for a 21+ year old abs sensor that can fail at any time and can be replaced for £30ish.

I had the same problem as you and it was the sensor. Think about the cost and risk involved with rounding off or snapping the driveshaft bolts etc, it's much safer to spend the 30 on a new sensor.