Q: po420 code went on, what are chances that it is actually my catalytic converter

asked by on March 14, 2017

po420 went on, what are chances it's actually catalytic converter

My car has 170000 miles.
My car has an automatic transmission.

Hello, thank you for writing in. A catalytic converter going bad after this amount of mileage is not unheard of. Although you will definitely want to check the oxygen sensors first. If you are in a position to test them electronically, then you can do so with a multi-meter. If you are not able to test them, make sure there are no other codes besides the P0420 (such as one that would indicate a fuel related issue, or a spark/timing related issue), and then go ahead and replace the downstream sensor. They are cheaper and easier to change out at home than the catalytic converter. You can also have your emission tested to make sure the cat is doing its job, before replacing anything. For more help with diagnostics or repairs, contact our service department to schedule an appointment.

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