Check Engine light with Code P0420

Hi All,

I got the check engine light on just before a week. In fact this happened two times before. Once I had to change the egr valve to fix that. Now again i got that light on. I went to autozone for the code reading and found that "P0420"...Catalytic system efficiency below threshold. It this a serious problem? Can this cause anything bad to my car. I have 144K mile on the odometer. So I don't want to spend more. Is there any cheap fix? What might be wrong? Any idea?

Thanks,
PK

Pretty good bet that it is an oxygen sensor.

You most likely have a bad cat. converter. This code is saying that the readings of the oxygen sensor before the converter is almost the same as the sensor after the converter, meaning the converter is not doing its job. A scan tool can easily diagnose this by watching the wave forms of the two oxygen sensors, they shoud be competely different. If the wave forms are the same, then the cat. it shot.

Is there any big problem if I will NOT fix this and continue driving?

Thanks for all the suggestion.

PK

your problem would be during emission testing.