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it means your warm-up catalyst in your O2 front sensor is not working. i know b/c I'm replacing mine right now, got the same code reading at the garage.
you can get them online a lot cheaper than at the garage. garage wanted to charge $110 for one, but i found the same one online for $50.
What else can I help you with?
P0421 check engine code on 2001 Mazda 626?
Trouble code P0421 means:Warm up catalyst system efficiency below threshold
Mazda 2001 protege lx P0421 error code?
Trouble code P0421 means:Warm up catalyst system efficiency below threshold
What is 1999 Mazda Miata check engine light code P0421?
Trouble code P0421 means: Catalyst Efficiency Below Normal (Bank 1)
Ow do you correct the Check engine light on your 1998 Mazda protage with the code of p0421?
Trouble code P0421 means: Catalyst Efficiency Below Normal (Bank 1)
1998 Mazda 626 p0421?
Trouble code P0421 means: Catalyst Efficiency Below Normal (Bank 1)
What is the engine check code P0421 on a 04 Mazda mpv?
PO421 Warmup Catalyst Efficiency Below Threshold Bank 1Possible Causes: Defective spark plugDefective O2 SensorDefective Catalytic Converter
Mazda Millieum S 2000 emission code P0421?
Trouble code P0421 means: Catalyst Efficiency Below Normal (Bank 1)
What does engine code P0421 mean?
P0421 code = Warm up catalyst efficiency below threshold, Bank 1
1999 Mazda protege 1.6L engine died while driving under normal freeway conditions. Engine wouldn't crank had to wait 5 minutes to restart. Have new post cat O2 senor but got P0421 code. Ideas?
i had a similar problem before,usually if your running lean it could be the fuel pump.if not fuel related then check ignition system modules sometimes overheat and cause car to shut down then come on once cooled down.
What is code p0421?
P0421 : Warm up catalyst efficiency below thresh hold bank 1
What is OBDII code P0421?
P0421 : Warm up catalyst efficiency below thresh hold bank 1
What is code p0421 on audi a6 2002 3.0 bank 1 02 sensor?
Passenger side and after the catalytic converter O2 sensor.
