A4 2.5tdi Cab Abs Warning Light

[hugo1]

Hi, i wondered if anyone can shed any light on a problem i've got. i set off in the car and every-so-often i'll lose ecceleration then the abs warning light comes on. after a while the light goes out again and the car is back to normal. there are not other warning lights that come on at all. any ideas would be appreciated, thanks in advance.

[audipersempre]

Most likely are:

a) Dirty or slightly out of alignment abs sensor
b) Fauly abs sensor
c) Dirty reluctor ring
d) Damaged reluctor ring
e) Low brake fluid level (not sure about this one!)
f) Faulty abs unit

Do you understand how abs works at the wheel end? My explanation might be crude and not word for word accurate but it's close enough!

Best analagy I can use is it's like a bicycle with one of those cheap speedometer / distance things. You have a sensor which couts the wheel spokes as they go by.

Same on the car. The abs sensor counts teeth on the reluctor ring on the drive shaft as the wheel goes round. If either is dirty, damaged or faulty you will get an abs fault light.

First check for dirt / physical damage then best take to a garage for electrical checks.

As an example. On the 800 series Rover the bracket holding the sensor warps over time and the sensor goes out of alignment. Many people replaced their sensors at a significant cost only to find the fault didn't go away and replacing a 50p bracket would have solved the problem. Ask me how I know.........:(

Hope this helps.

[hugo1]

Thanks for your help Steve. sorry to hear you found out about these problems the hard/expensive way. may just save me some money though! cheers again.:beerchug: