xs2kFanaticx

Hey guys, i have an 07 s2000, just replaced the cat about a few days ago. I had no CEL come on until after 100 miles, and just got one today. Code pulled up as P0420, which is the catalytic converter code. Now my cat is brand new, the guy at auto zone that pulled the code for me stated that its the bank 1 o2 sensor, but some other people are saying it could be both bank 1 and bank 2 o2 sensors, I was told when the bank 1 o2 sensor gets messed up it could cause the second one to get messed up as well? I had originally had a test pipe on the car for about 2 years or so, and took it off and placed a replica brand new OEM cat on the car a few days ago. I just need some help determining whether it is just the first o2 sensor or maybe both, any feedback would be helpful, thanks!

Currently put my car back to stock to sell the car

07 s2000

Slows2k

Replica cat? Get a OEM one.

Billman250

for the two years you had the test pipe you had no CEL? How did you do that?

xs2kFanaticx

I did have the CEL with the test-pipe, but now placing a new CAT, it comes on after a few hundred miles, it's weird I'm trying to figure out if its my o2 sensor or not. So far I reset the light and it hasnt come on and I have driven for 120 miles so far. Any ideas?

xs2kFanaticx

It's a brand new CAT, it can't be the CAT.

Slows2k

If it's a brand new aftermarket converter in can be faulty. Aftermarket converters are well known for not passing catalyst monitors.

xs2kFanaticx

If that is the case, how come my CEL comes on after 200 miles? Is that normal? I don't understand, so far I've reset the light and ive driven over 120 miles and no CEL lite, could it have been a glitch? I've heard some people on the forum stating they reset the light and it never came back on. A brand new cat can be faulty? The CAT works perfectly fine.

Slows2k

The catalyst monitor takes 2 trip to turn on the CEL. You can't claim the catalyst works fine if you have a P0420 stored, you can still have a faulty converter. There is not set mileage when the CEL will come on with a 2 trip DTC.

xs2kFanaticx

The auto zone guy that checked the code, said it was the bank 1 o2 sensor, he's like he doubts it's the CAT, could it be the o2 sensor?

Slows2k

P0420 is for the catalyst, not a 02 sensor. Did you get another DTC?