Q: Code P0420

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I have the check engine lite on code reads po420 before bought car it had no matience for over 3 years the trans fluid is very dirty and black can this be the cause

My car has 1344449 miles.

Code P0420 relates to an issue with the catalytic converter performing at a less than optimum level. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When the catalytic converter is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

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