مرحّل سخان الحفاز معطل

The relay powering an electrically heated catalyst, failed so the heating element never energises. Heated catalysts exist to reach light-off temperature within seconds of a cold start, when most of a journey's emissions are produced, and they draw very high current — which is why a relay rather than a module output switches them.

The module monitors the circuit and reports it, so the code names the heater while the element is undamaged. The fault is invisible to the driver: the engine runs normally and only the emissions performance changes, so it is typically found at a service or a test.

Relays switching this much current wear out, and their contacts pit and eventually weld or fail open. Substitute an identical relay as a first test, which is free and definitive. Ask what killed it if it has welded — an element drawing above its rating welds the replacement too, so measure the element's resistance before fitting a new relay.