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Discussion Starter · #1 ·
so, ive got a cel on and its the p4020 or something like that. i took it in and it said 1st bank below threshold or something? not really sure what i should do now.
 

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I <3 My Honda
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obd-codes.com/P0420

It's just your oxygen (O2) sensor. No biggie, they go bad. You could try resetting the code and seeing if it comes back.
 

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Discussion Starter · #3 ·
so it doesnt mean the cat is clogged because my gas mileage as been real shitty recently and even on these cold days it really doesn't look like much exhaust is coming out of the tailpipe
 

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A bad O2 sensor can destroy your MPG and hog gas due to the gasoline / oxygen ratio being inadequate/incorrect. Why start with the most expensive thing first (cat converter)? O2 sensors don't break the wallet and are easy to replace. I'd start off by resetting the code and seeing if it comes back. If it does, then replace the O2 sensor.
 

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so, ive got a cel on and its the p4020 or something like that. i took it in and it said 1st bank below threshold or something? not really sure what i should do now.
DreaminAccord is correct. Start with the cheaper options rather than just throwing parts at it. Reset the code, and if it comes back replace the O2 sensor that is throwing the code. Then if the code comes back on with a new O2 sensor, you know it's something bigger. At that time we always recommend having a shop take a look to see what is really going on.
 
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