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by (101 points)

Our 2011 Ford Fiesta S 1.6L I4 check engine light came on & OED is giving a P0420P code. What would be best thing to start with checking? We haven't had the car very long at all & wanted to ask before I take it to a mechanic in case it's possibly could be something easy to fix that we can actually do ourselves. But if it's possibly multiple things that could be the issue & will need to be checked I'll prolly just take it to shop instead. Just hoping someone can tell me anything to narrow it down hopefully at least so I know what to expect them to say anyway. Thanks for any help with this issue.

Vehicle: 2011 Ford Fiesta S 1.6L I4

1 Answer

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The P0420 code is usually for the Catalytic Converter. In some rare occasions bad gas, faulty spark plugs, exhaust leaks or faulty oxygen sensors can also set the code, but the catalytic converter is the most frequent problem. My only recommendation is to clear the code first, use high-octane gas for a few weeks, and if the code comes back, then you can take your vehicle to the shop for further inspection.

P0420 Ford Code - Catalyst System Efficiency Below Threshold Bank 1
Read more: https://www.autocodes.com/p0420_ford.html

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