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Q: Diagnosed as code P0420

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The Engine light came on. I went to the mechanic an it was diagnosed as a code P0420.

A: When you get a P0420 code that indicates a ...

When you get a P0420 code that indicates a failing catalytic converter. Most of the time that is exactly what it is. In some cases, it can also be caused by a bad oxygen sensor. I typically use a computer scan tool to monitor the signal coming from the oxygen sensors. If they are not reading correctly then they need to be replaced. If they are fine then the catalytic converter needs to be replaced. If you would like to have this repaired, consider YourMechanic, as a certified mechanic can come to your home or office to make a diagnosis and to replace either your oxygen sensor or catalytic converter.

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