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P0421

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P0421 OBD-II Trouble Code: Warm Up Catalyst Efficiency Below Threshold (Bank 1)
P0421 Code Definition Warm Up Catalyst Efficiency Below Threshold (Bank 1) What the P0421 code means The P0421 code means that the powertrain control module is noticing that the...

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Question
P0421 and P0401 codes have appeared
Hello. The codes P0421 and P0401 refer to the oxygen sensor and EGR valve, respectively. It is possible that an issue with one is causing the fault to be seen by the other, as they will work loosely together. It...
Question
P0421 comes up on scan. What is the likely culprit
Hello. When you get the P0421 code, it usually means that you have a failing catalytic converter. It is very common for converters to fail on this vehicle over time. Most of the time I use a scan tool to...
Question
P0421 code and wheel bearing
Hi there. The P0421 error code typically indicates that the catalytic converter is wearing out and needs to be replaced. However, it could also be sensors that are damaged sending false information. In regards of the wheel bearing, that rubbing...

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