P0420 error

[stevepen]

Had the mil light on today with the error P0420. Looking it up says cat isn’t fully functioning. Is this due to an O2 sensor? It’s a 2001 2.0 vvti

 

 

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[KennyKen1988]

It's a very generic code, but yes an o2 sensor issue is a likely cause, along with an exhaust / catalytic converter failure.

[stevepen]

It's a very generic code, but yes an o2 sensor issue is a likely cause, along with an exhaust / catalytic converter failure.

Thought it might be. Anyway to tell which one? I reset it and drove around this afternoon and it’s not come back yet so can’t see it being the catalytic converter.


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[KennyKen1988]

For the sensors ideally you need to look at the live data streams and see how the sensors are reacting. I believe you can tell there is an issue when the post cat sensor is mimicking the primary o2 sensor and look our for irregular drops or spiking. Also with the sensors removed you can do tests with multimeter and applying heat to the sensor probe. Give it some and time and it will typically return possibly up to a week or a few drives depending how often you drive.

 

 

[stevepen]

Just to update this thread. I reset the error but it came back after a week. Put a bottle of Cataclean in that I’ve used before. Now a month in and 1500 miles and the errors not come back [emoji1696]


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