C3 ABS and traction problems

I had similar ABS and traction issues on my C3. Check the ABS sensors first. A faulty sensor can throw off the whole system. The speed signal fault makes me think it might be related to one of those sensors.

Thanks for the tip! Did you have any luck cleaning them, or were they completely shot? And did you happen to notice if your speedometer or odometer were acting up at all at the time?

Cleaning didn't work for me. I replaced the sensor, but the issue persisted. It turned out the affected control unit was defective. I'd suggest getting it checked by a workshop before throwing parts at it. Expect around 1000€ for the repair.

Appreciate the insights! Took it to the workshop, and you were spot on – defective control unit. Looks like I'm in for the 1000€ repair. Thanks for pointing me in the right direction!