P0421 Diagnostic Trouble Code Discussion for February 2010
Warmup Catalyst Efficiency Low (Bank 1)
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| Help Request | Posted | |
| 2001 Mazda Millenia 2.5L MIL Lamp on VIN: JM1TA22141 P0421: Catalyst Efficiency Below Normal (Bank 1). ... among other things it fails emission for 2 codes in computer. p0421 and p0431 catalyst efficiency below threshold bank 1 and 2. plugged scanner in and found upstream and downstream were doing the same switching on both banks which tells me that the cats ar... |
February 08, 2010 | |
| 2002 Mitsubishi Lancer ES 2.0L MIL Lamp on VIN: JA3AJ26E12 P0421: Warmup Catalyst Efficiency Low (Bank 1). ... cat does a melt down at end of cat,and needs new oem, and flash. With the feed to O2 heater,I have 12 volts,but I can't light a test light,red and blue wire,from mfi relay and pcm.If I have a O2 heater problem,that would cause the P0421 ,right,and I would ... |
February 12, 2010 |
