CEL again

[Sudhir]

Can someone please help. The first time I had CEL I got error code P0171 and P0300. I changed the MAF sensor. After driving about 200 miles I got the CEL again.

This time the error code is P0420.
Any suggestions?

[TenZen]

P0420 Catalyst System Efficiency Below Threshold (Bank #1)

could be the O2 sensor is going out of the cat its self.

[Sudhir]

Do you think I should replace the O2 sensors?

[TenZen]

wouldnt hurt. if you were going to get a cat, you were going to have to replace the 02 sensors anyway. there like between 70-90 dollars and a cat in the hundreds.

[Sudhir]

Should I replace both the sensors? Money is tight. Car is running fine, suggest something please.

Should I buy the O2 sensors with the connectors? And how much do mechanics usually charge changing them?

[Tavel]

Originally Posted by Sudhir

Should I replace both the sensors? Money is tight. Car is running fine, suggest something please.

Should I buy the O2 sensors with the connectors? And how much do mechanics usually charge changing them?

rule of thumb: the front O2 sensor controls fuel mixture, the rear sensor controls emmisions.

You can test the sensors instead of blindly replacing them, I'm not up on the procedure but you should be able to find it in a decent repair manual.

[REN69]

Originally Posted by Sudhir

Should I replace both the sensors? Money is tight. Car is running fine, suggest something please.

You decide, if the car runs ok and it doesn't bother you to wait till you got the money then go for it. We can't really tell you what decision to take.