Aygo ABS Lamp and Control Unit Failure

Whoa, that sounds rough! A defective control unit is never good news. Speed signal fault could mean a few things. Is your speedometer working okay? It could be a faulty ABS sensor, which is way cheaper than the control unit itself. The ECM is responsible for speed signals and if the ABS isn't working, the ECM might be involved as well. Have they checked the ABS sensors individually?

The speedometer seems to be working fine, which is weird. So, if it's not the ABS sensors and the speedometer's okay, does that definitely point to the control unit being the problem? What does ECM stand for?

ECM stands for Engine Control Module - basically the car's computer. If the speedometer is working, and they've ruled out the ABS sensors, then yeah, it's unfortunately looking more and more like the control unit. That price sounds about right for a new unit and labor, though. I'd suggest getting a second opinion from another workshop, just to be absolutely sure before spending that kind of cash.

Thanks so much for the advice! I took it to another workshop as you suggested, and they confirmed it was indeed the control unit. Ended up getting it replaced, and everything's working perfectly now! Cost me pretty much what they quoted, around 1000€, but at least it's fixed. Really appreciate the help!