P0421Warm Up Catalyst Efficiency Below Threshold (Bank 1)

This is like P0420 but for the warm-up (close-coupled) catalytic converter on bank 1, the one mounted close to the engine to light off quickly after a cold start. The computer determined this converter is not cleaning the exhaust efficiently enough. Usually the converter is aging, but sensor or exhaust-leak faults can also cause it.

Ամենատարածված պատճառներն են՝ Worn-out or failing warm-up catalytic converter (bank 1), Failed or slow downstream O2 sensor, Exhaust leak near the converter or sensors, Engine misfire or wrong fuel mixture damaging the converter, Oil or coolant contamination of the converter։

Սովորաբար անվտանգ է կարճ տարածությունների վրա վարել, սակայն շուտով ստուգել տվեք։

Short trips are generally fine since this is an emissions issue, not a safety one. Get a proper diagnosis before replacing the converter, as a bad sensor, exhaust leak, or misfire can mimic or cause this code. Resolve any underlying engine fault first so a new converter is not damaged.