P0420 Code

[Luke_Green]

I keep throwing a P0420 code says "catalyst system efficiency below threshold bank 1" my car hesitates sometimes when shifting its rare though and I read that it could be a bad cat causing the tranny to slip. I have inspection next month and I need to get rid of the engine light. I tried the 02 sensor spacer on bank 1 not 2 and the light came back on. Im trying to find out a way to not spend money on a new cat. Any suggestions?

 

[hswan1180]

I keep throwing a P0420 code says "catalyst system efficiency below threshold bank 1" my car hesitates sometimes when shifting its rare though and I read that it could be a bad cat causing the tranny to slip. I have inspection next month and I need to get rid of the engine light. I tried the 02 sensor spacer on bank 1 not 2 and the light came back on. Im trying to find out a way to not spend money on a new cat. Any suggestions?

New sensor?

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[Luke_Green]

New sensor?

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If I were to replace the 02 sensor since the code is saying bank 1, which is the upstream 02 sensor, would it only be that sensor and definitely not bank 2 sensor?

 

[hswan1180]

If I were to replace the 02 sensor since the code is saying bank 1, which is the upstream 02 sensor, would it only be that sensor and definitely not bank 2 sensor?

Yes that is how the OB2 identifies one from the other. At this moment i can't remember the location of bank1.

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[Luke_Green]

Yes that is how the OB2 identifies one from the other. At this moment i can't remember the location of bank1.

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I know the 02 sensor thats right after the headers kind of before the cat is for air fuel ration is that the bank 1 sensor?

 

[hswan1180]

I know the 02 sensor thats right after the headers kind of before the cat is for air fuel ration is that the bank 1 sensor?

Sorry i cant be of much help at the moment... My book is at the house. This might help.

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[Luke_Green]

Sorry i cant be of much help at the moment... My book is at the house. This might help.

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Yeahh Ive been doing more reading about it bank 1 doesn't mean a specific sensor so I am going to try putting the 02 sensor spacer not on the A/F ration sensor I'm gonna try spacing out the 02 sensor thats after the cat hopefully it fixes the CEL.

 

[XpL0d3r]

^ A failing secondary 02 sensor can trigger the code but it's highly unlikely.

@Luke_Green P0420 means there's not much of a difference in reading between the primary and secondary 02 sensors. The first sensor controls A/F ratio when at normal operating temp, but both also ensure the cat is doing its job. The first sensor takes an emissions reading of the exiting exhaust gases. The gases go through the cat, reducing emissions. Then the secondary sensor reads the gases again to ensure the cat did it's job. If the readings are too similar, P0420 pops up. It's likely that the issue is with the catalytic convertor.