a lady I work with on occasion has an '01 NFR. she loves the car, but doesn't really give it the care it deserves. at her annual emissions test, the car failed to pass. she was given paperwork with the following code:

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

I searched the board and found some people say it was the secondary o2 sensor and others said the catalytic converter was dead and needed to be replaced. any definite answer on which it is?

I wouldn't be surprised if the cat was dead really since I don't know the mileage, overall condition of the car, or maintenance habits. in past discussions, she said she doesn't like to use premium gas because it's too expensive.

 

I would think O2 sensor only because the list I have says that P0422 is "Main Catalyst Efficiency Below Threshold." I would imagine that would mean converter, but I dunno. Tell her to replace them both and then ask how much better she likes using premium gas instead of replacing expensive parts.









(p.s. I don't really know if using regular gas would mess up something like that or not, but I'm not going to find out.)

 

thanks Russ. I'm going to suggest she pull the neg battery cable to see if the CEL goes out completely or comes back. next would be the o2 sensor. and lastly the converter if it comes to that.

 

Ha, the good ole P0420. I was running catless on the wrx and wanted to get P0420 as my license plate.

 

Man I am glad I do not have to use O2 sensors. Best of luck, let me know if you needs parts, I can save you some money.

 

I see that code on a daily basis. Its most always the convertor.

 

I have a cat if she doesn't want to buy a new one.

like 45k miles on it.

 

That's AWESOME. So few ppl would get that... then there might be that ONE cop that might...

Jake's got a coupla (LM) cats on hand...

 

wait, wait, I meant (DTM) cats...

 

as do i