P0421 Diagnostic Trouble Code Discussion for September 2006
Warmup Catalyst Efficiency Low (Bank 1)
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| Help Request | Posted | |
| 2000 Mazda MPV DX 2.5L MIL Lamp on VIN: JM3LW28G3Y P0421: Warmup Catalyst Efficiency Below Normal (Bank 1). This Mazda is back with the same codes. All scan data looks normal except for post warm up cat sensor activity. A search of the archives shows that some Mazda's had a re-flash for these codes, but none seem to be available for this one. No TSB's listed in Alld... |
September 10, 2006 | |
| 2000 Audi A4 2.8L MIL Lamp on VIN: WAUDH28DOY P0421: left bank warm up cat below efficiency. We have four scan tools in the shop and cannot monitor both oxygen sensors to test cat, efficiency. I suspect that both cats are bad but hesitate to replace them and have a repeat failure. Does anyone have advice about what the cause might be or is this a comm... |
September 13, 2006 |
