Showing code P0420 for the last 4 months.

Asked by Apr 09, 2017 at 06:01 PM about the 2010 Honda Accord LX

Question type: Maintenance & Repair

Engine light was on. Showing P0420 (since 4 months). Dealership quote was
too expensive, they said catalytic converter needs replacement. Engine light
disappears/appears frequently. Don't have too much money to spend.
Please let me know how to proceed on this issue to minimize expenses. Is is
due to O2 sensors, or a choked and defective catalytic converter?

1 Answer


You should go to a independent exhaust shop if the catalytic converter needs replacement. After market cats are much cheaper than the OEM. Plus their labor rates would be lower than the dealer. The P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

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