صمام إمداد وقود العادم عالق

The valve controlling fuel to the exhaust-side injector, stuck. It is the shutoff upstream of the injector, and it exists so fuel cannot reach the exhaust when none is commanded.

Stuck closed, regeneration cannot happen — the injector is commanded and no fuel arrives, so the filter loads and the module reports the injector's performance. Stuck open is the serious direction: fuel can reach a very hot exhaust uncommanded, which risks over-temperature and damage to the aftertreatment. Exhaust temperature rising when no regeneration is running is the signature of the open case. Check this valve as well as the injector when a leaking injector is suspected, since a valve that does not seal produces identical symptoms with a sound injector.