To be totally honest I'm not sure what the exact test procedure is... I believe that the front one on the manifold is the same so you could always "swap" the two, clear the code and see if a new code comes back or the same one comes back, if the same one comes back then it indicates a CAT issue not a sensor issue, if it throws a different code to indicate the primary sensor then you know your sensor is bad...

 

Okay I replaced my O2 sensor with a Bosch sensor and the lights gone for now after restarting it. I'm hoping it stays gone. I'll post here again if unfortunately the light comes back on.

 

Okay my check engine light went on again and I got the same P0420 code again. I'm thinking of just leaving the check engine light on, I mean it's only natural that it would go on if I put on something aftermarket on my car. When it comes time to sell the car I"ll think of something then.

 

P0420 points to a bad cat. On a 98-02 accord it's an almost sure thing.

 

A bad cat? I have an aftermarket Magnaflow cat it can't just go bad can it? Is there a way to tell if my cat is working or not? Because if on a rare occasion my Magnaflow actually did screw up due to manufacturer defects I'll have to ship it out to have it fixed, which will be a pain since my cat's welded onto my headers already.

 

Heeeeee

Where's the o2 sensor located on it? At the front or back of the cat?

 

It's on top, if that's what you're asking. So if I was completely underneath the cat looking up at it, I wouldn't see the hole where the O2 sensor goes.

 

Nope front or back is what i was asking. It should be towards the back. If it's at the front the cat was installed backwards and that would be the cause of it coding.

 

Wow something as stupid as that? I'll have to see again but I do think it might be in the front. Even if it is like 1 cm away from what would be the "middle'" of the cat that would mean that it is in the front? Meaning that it was installed backwards? I guess I would have to go back to the damn place to have it fixed. Does it affect performance in any way?

 

since it's a high flow cat it's giving you the code because it's reading different than stock, an emulator or simulator O2 sensor will fix that issue.... either that or go back to a stock cat... Leaving the light on isn't a good idea though, because if something else fails you won't know it until it's too late