I have a 2010 F-150 with a 5.4 engine. It kept showing codes P0420 and P0430. I’ve fixed the issues, but now the codes are permanent. I have 3 different scanners, and none of them will clear the codes, even with the key on and the engine off. How can I get the truck to complete its drive cycle and clear the codes?
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Check for engine mechanical issues. Worn piston rings, leaking valves, and other internal engine difficulties that cause an excessive amount of unburned gasoline might eventually harm the catalytic converter.
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The catalyst efficiency diagnostic must run and pass for the codes to go. Cats with hollowed out bodies will not assist, and the diagnostics will continue to fail. Cat lights must be turned off, and holy cats will not do that. Obtain some cats with strong flow and try it out.
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P0420 and p0430 codes are efficiency codes when means the o2 sensors are reading and do not like what they are seeing. Those codes mean your catalyst is not efficiently filtering the exhaust. Did you replace the stock catalyst with a factory one or aftermarket? You should have a parts warranty.