P CODES (POWERTRAIN) P0400 - P0499 P0421 Questions

Car: 2002 Mazda 626 Lx 4cyl 2.0l The Check Engine Light With Code P0421 Goes On When The Car Run City Miles, And Goes Off When Running...

Check Engine Light On, How Do I Fix This? Any Ideas Of The Cause?

I Have Already Replaced My Rear Catalytic Converter And Downstream O2 Sensor Along With Fixed Exhaust Leaks. Map Sensor And I Know I Have A...

This Car Use Only 60,000km.and The Engine Check Light All Get On. The Fault Codes Are P0421 And P0431. We Suggested The Customer Use Some...

Car Has Check Engine Light On .. I Changed The Cat On The Bottom Of The Car But Still Has Light On.. I Understand That It Can Be A O2 Sensor...

Engine Performance Problem 2001 Mazda Mpv 6 Cyl 141000 Miles My Car Tries To Start , Then Shuts Off After About 3 Seconds, I Keep...

Obd Code Po421 Is Registering On My Car. According To What I'd Read It Means The "warm Up Catalyst Efficiency Is Below Threshold Bank 1...

This Morning P0301 Code Pop Up In The Pending Code Category. I Have P0421 Code Which Is Related To Catalyst 1 Efficiency Below Threshold...

I've Been Having Trouble With Code P0421... I Had The Catalytic Converter Replaced And It Went Away. Two Days Later The Check Engine Light...

I Have A 2000 Montero Sport. Got Code Po421 And Have Sequentially Replaced All 4 O2 Sensors In Addition To Having A Complete Tuneup...