Q: Q: I have the P0420 code

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My check engine light is on and I have the P0420 code

My car has 240240 miles.
My car has an automatic transmission.

Hi there, thanks for writing in. Code P0420 has to do with the catalytic converter in your vehicle. The code will need to be diagnosed by checking the vehicle for exhaust leaks, O2 sensor problems, or the wiring to the sensor damaged. If all these check out then the catalyst my need to be replaced. The most common failure for this code is the O2 sensor not working correctly and needing replacement. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

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