ABS fault light on

wigtonman · Post by **wigtonman** » Thu 21 Jul, 2011 18:55

Can anyone offer advice on the cause of the ABS fault light being on continuously, not on yesterday but when started car this morning ABS and exclamation mark in a triangle remain on.

pingu · Post by **pingu** » Thu 21 Jul, 2011 19:45

Lots of help on the search facility, but

My guess is either a broken wire or a dirty sensor.

swamper · Post by **swamper** » Thu 21 Jul, 2011 20:35

dont panic..!
it happens all the time with some cars...give it a few days and plenty of of off and ons to see if it picks up the sensors again as pingu says it probably a dirty sensor.

wigtonman · Post by **wigtonman** » Fri 22 Jul, 2011 08:48

Thanks for those replies, I'll have a look underneath to see if I can identify the rotation sensor which may be causing the problem, would the computer diagnostic identify which sensor is giving the problem?

Guest · Post by **Guest** » Fri 22 Jul, 2011 09:04

The sensors are easy to remove, but be careful not to damage the wire sheath which is quite fragile and also, don't lose the circlip that keeps the sensor in place, it's tiny.

RemarkLima · Post by **RemarkLima** » Fri 22 Jul, 2011 12:43

wigtonman wrote:Thanks for those replies, I'll have a look underneath to see if I can identify the rotation sensor which may be causing the problem, would the computer diagnostic identify which sensor is giving the problem?

Yep, diagnostics will tell you exactly which sensor is playing up or if it's a later car with DSC, then it could be the stering angle sensor, brake pressure sensors etc...

Mine had the ABS light on permanantly when I first picked it up, so was pretty much definately a duff sensor (if it only comes on once on the move then it could be just dirty)... A quick diag read and it was the rear right sensor.

freelandm · Post by **freelandm** » Fri 22 Jul, 2011 13:57

You need to get the code read and hope it isn't the pump as it was on my car.

Regards Matt

Taz-Devil · Post by **Taz-Devil** » Fri 22 Jul, 2011 21:32

very common problem on z3s its the abs traction senser
you will find hundreds of posts on this subject
the senser sits on inside of the hub on each wheel
its held in by a allen key bolt front ones can be in very tight
its normal some rust or dirt gets on and sticks to senser
9 out of 10 times cleaning cures the problem
just done mine again

wigtonman · Post by **wigtonman** » Sun 24 Jul, 2011 07:18

Thanks again for the responses to my problem, I'll get the wheels off and remove the sensors and clean up.

wigtonman · Post by **wigtonman** » Sun 31 Jul, 2011 06:52

I have managed to get the rear rotation sensors out and give them a clean but not the front ones they are well suck. Is there any means of resetting the system other than by a lap top to see if what I have done up to know will reset the fault indication. Both rear sensors had dirt on the sensor faces.

John Wilson · Post by **John Wilson** » Sun 31 Jul, 2011 10:58

As swamper says, the system will reset itself if the problem has been cured. The front sensors are more likely to be the problem as these pick up more stuff from the road then the back ones. Lots of wd40 over a few days could get them moved, but the important thing is not to put to much pressure on the allen bolts because they sheer off quite easily which would mean drilling out and retapping. I think that if you have to destroy the sensor itself getting it out it is not such a problem as they are not expensive. Once it is all sorted out, it is really worth taking the sensors out for cleaning regularly to prevent them seizing in again.

RemarkLima · Post by **RemarkLima** » Sun 31 Jul, 2011 10:59

I think the system resets everytime you start the car, the fault is just logged from before and you'll need diagnostics software to clear the fault logs.

So, if both rears have been cleaned then it'll be the fronts... These are pretty cheap if you need to replace them.

A quick run on the diagnostics would show the exact wheel that's causing the problem, so well worth it to remove the guesswork.

Bill- · Post by **Bill-** » Sun 31 Jul, 2011 15:48

Best way to see if its a sensor problem drive down a dirt or loose surface road & apply brakes hard if it judders in quick succession abs is still working.. if car skids you have no ABS goodluck..

PS the warning lights do work on BMWs, so its likely you have a prob with abs.. its the brake wear sensors that fail..

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