p0420 code fix

Question

i have a 08 chevy malibu 4cly reading the code p0420. i read it could be several things but most likely its either the downstream oxygen sensor or the catalytic converter. the car is getting bad gas mileage and is real weak, you have to mash it to pull off. i would assume it is the catalytic converter considering the power loss but i would like to be pretty sure before i buy the converter because its not cheap or a quick fix. a sensor would be nice. what do you think it may be and is there a way to find out what it is without replacing each possible issue? thanks

Answer 1

Hi Joey,

The only way to determine if the converter or sensor is the issue is with a scan tool. With a scan tool you can watch what the rear O2 sensor is doing. The voltage on the sensor is generated by the oxygen maing contact with the sensor. You can also unbolt the converter and check and see if it's plugged up. Based on your sysmptoms sorry to say it sounds like the converter is the problem.