p0431 fix??

The on board computer in your car uses the readings it sees from your oxygen sensors in the exhaust to determine if the catalytic converters are working efficiently or not. A P0431 is set when the computer sees a problem related to the efficiency, it can be caused by a bad catalytic converter or bad O2 sensor/sensor heater circuit (testing is required to determine either). No cheap answer here unfortunately and our laws here in CA require OBD2 authorized catalytic replacement cats only. Mitsubishi outline detailed criteria conditions it looks at for testing, and an oscilloscope used to compare front and rear O2 sensors at the same time is best to see if the sensors are working correctly.