2003 Peugeot 206 ABS

There is going to be a diagnostic fault code stored in the Anti-Lock Brake Computer. It will not say to replace a part but it will indicate the circuit or system that needs further diagnosis. Your mechanic will connect a scanner to read that code.

Also be aware that if you wait a long time to fix this, a second, totally different problem can develop but not set its own fault code. Every fault code has a long list of conditions that must be met to set that code, and one of those conditions is that other codes related to things used for comparisons aren't already set. When that happens, your mechanic won't know about that second problem until after the first one is diagnosed and fixed.