ABS Light Audi A3: Causes & Fixes

Hello!
"Hi, I have an A3 1.8L, but it shouldn't be too different. I'm having a problem where the ABS light is coming on more and more frequently. At first, it was rare, and it would occasionally light up on the highway without me braking, suddenly, and then it would go away after turning the engine off and on. But now it's coming on more often, and sometimes it even stays on after a restart. The error memory says "hydraulic pump, signal outside of tolerance, sporadic." What could this be? A loose connection? Yesterday, I just drove down a curb, and it came on again! I have a 60/40 lowering kit. Does anyone have any ideas?"

Thank you.
Martin.

I've had the pleasure of the ABS warning light illuminating twice so far.
Both times, a wheel speed sensor for the ABS was defective in the front.
However, this error was correctly logged in the vehicle's memory each time (once on the left side, once on the right side).
After the replacement, everything was fine again.

What is your kilometer performance?

For me, it was around 200,000 [units/miles/kilometers - context needed].

Best regards, D.

I also had a similar problem with my Golf II. It was also a defective wheel sensor (rear right). The error could initially be reset by turning the ignition on and off, but one day it appeared permanently. I measured the wheel sensors, and in this case, the resistance was 1 kOhm. There was no continuity. I performed a test with a 1 kOhm resistor. The ABS light went out. I drove to the "friendly" dealer and almost tipped over. 181 DM!

But your control unit is telling the hydraulic pump something. That will be more expensive. However, these things are supposed to sometimes be wrong. In any case, with the Golf, I was able to start troubleshooting completely free from electronic diagnoses.

Regards,
mcgregg

1. Remove the lamp from the instrument cluster (this is probably the easiest part).

2. Check the connectors to see if there's any oxidation.
3. Measure the cables.
Replace the 4th control unit (or module).

And also check if the ring on the wheel sensors is getting clogged with dirt.

Good luck.

"Mine has 160,000 km on it. Yesterday and today, the light didn't come on, so I don't think the pump is broken. The ABS is still working for now. I'll probably have to clean everything. Thanks!"