Code P0420

Hello, I'm Danny.

Yes, with that amount of mileage and the condition being set from the prior engines performance I would say it might be time for a new catalytic converter. Here are a few converter tutorials for you to view:

https://www.2carpros.com/articles/bad-catalytic-converter-symptoms

https://www.2carpros.com/articles/catalytic-converter-replacement

I've attached picture repair steps below if you want to test. Hope this helps and thanks for using 2CarPros.

Good morning,

I attached the procedure and some pictures for replacing the catalytic converter converter for you.

The easiest way to test is use a scan tool and monitor the rear O2 sensor reading. It should be steady. If it varies up and down the cat is bad.

Roy

REMOVAL
1. Raise the vehicle.
2. Disconnect the downstream heated oxygen sensor electrical connector.
3. Use the oxygen sensor wrench to remove the downstream Heated Oxygen Sensor (HO2S).
4. Remove the muffler and tailpipe.

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5. Remove the three nuts.

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6. Remove the Three-way Catalytic converter (TWC) and the exhaust outlet pipe frame brackets.

NOTE: The exhaust hanger bracket insulators can be reused if they show no signs of damage.

INSTALLATION
1. Install the exhaust converter inlet pipe gasket, the three way catalytic converter and the exhaust outlet pipe frame brackets.

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2. Install the three nuts.
3. Install the muffler and tailpipe.
4. Lower the vehicle.

Hello again.

Just curious to know the outcome of having your catalytic converter tested. Keep us updated and hope we can still help resolving this issue. Hope this helps and thanks again for using 2CarPros.

Danny-

You need an advanced scan tool that can read the downstream O2 sensor. You will be looking for a steady volt reading of around.496. It may vary up and down a little.

When the catalytic converter is bad, the downstream sensor will read like the upstream reading from 0 to 1 volt. If it reads that way, the catalytic converter is no good and must be replaced.

Roy

Hello again.

As stated in the catalytic converter test tutorial we sent you do you have access to an infrared or thermal test device? If you test the incoming heat into the converter as well as the output heat there should be a difference in temperature. If the heat coming out of the converter is lower in temperature than the inlet temperature then you will know the converter is plugged or malfunctioning. Due to the chemical reaction inside a catalytic converter the outlet temperature will always be higher than the inlet for normal function. Hope this helps and thanks again for using 2CarPros.

Danny-