Questions & Answers for: Mazda 421

2003 Mazda MPV diagnostic code 421. Previously had codes PO134, PO131, PO151, PO171, PO174, PO401, & PO121. The hose the air filter and the throttle was broken, and tha engine would not start. I ...

what does the code 421 mean engine light comes on and the po 421 01/01 is the code that comes up the p0421 code on this vehicle is either caused by a bad catalytic converter or an oxygen sensor. your ...