ABS & ESP light

[m8gic]

Hi all

I had a read of the previous post below regarding ABS & ESP and mine seems different.

Recently when I drive the ABS and ESP light illuminates, I checked against reflections and the brakes lights are not stuck on and still work as they should when I apply the brakes.

The vehicle still drives the same so have not noticed anything different in that sense

Stopping the car and restarting it usually clears it all up then the lights come back on after a short while.

I read about the brake sensor on other posts but can anyone advise me on other issues we can check

Thanks

Audi A4 1.9 TDI AWX 2002

[donynysmon]

The brake lights can be working but the brake switch can still be the cause of the ESP light coming on. I think the brake light switch needs to operate BEFORE the pressure in the brake system starts to increase. If the brakes are being applied very slightly (you may not even notice it) before the stop lights come on, that's enough to cause your problem. That's what happened on mine and a new switch cured it.


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[m8gic]

How much did the part cost you, was it a simple replacement

[donynysmon]

I didn't buy one, I managed to take mine apart and re-set it. Wouldn't recommend that, it was a pig of a job, springs and bits everywhere! If I had to do it again, I'd just buy one, they are about £13 on eBay. Think the part number is 1C0 945 511A. If you google "FYI, new Brake Light Switch installation procedures" there is a good guide for installation.


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[yorkshiregit]

Normally an ABS sensor, get a diagnostic tool , under £20 on eBay & it will tell you what is causing it. Worth getting the read & reset one, not the read only ones

[donynysmon]

Still sounds to me that it's probably the brake switch. The lights do not need to stick on for there to be a fault. If when you press the brake pedal and the pressure in the brake hydraulics increases just before the lights come on, from my experience that's enough to cause your fault. The brake lights need to come on when you touch the pedal - before any breaking action whatsoever. Good luck and tell us if you solve it!


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[Rob69]

Could be one of several things, ABS unit, wheel sensor, reluctor ring, brake light switch, etc. a scan of the module should flag a code up. Until you do that then it's just guesswork and changing things till you hit on the fault. If you buy a scanner be aware that a generic OBDII scanner will not cover the ABS / braking module, just engine ECU module.
For what it's worth though, I've had the same fault on my 2005 passat, and it was a dirty wheel sensor tip, which was wiped clean and been ok since.