Ok so my gf's car needed a new exhuast an the cat was, well, rusted to the bad midpipe. So my friend gave me his hi-flow and it went on fine. Problem is the CEL goes on after about a day. I rese the ECU twice. Now I dont have a code reader, nor has it gone to get the code read. Everything was fine untill the hi-flow went in and other than that, its bone stock. Any ideas?

 

prob o2 sensor, or a emission code, uh is there any more info you can give

 

O2 sim FTW

 

Not really. Other than me putting on the new stock exhuast and the hi-flow, nothing else was done. I reset the ECU twice, but after about 45 min of driving, the CEL goes back on. She uses 87 octane **** water, doesnt add anything to the tank like additives, an doesnt drive the car hard. Think she needs a new O2 sensor?

 

search-> 02 simulator

 

I read a post out there that had a fix for this problem. They welded another O2 bung on top of the bung already on the cat then installed the O2 sensor the added height took the O2 sensor a bit out of the faster moving ex gas and it was able to read correctly it would only be a few $$ to have a shop weld on another bung.

 

is it a real high flow cat that you put on or is it one of those cheap resonator looking high cats that you get off ebay. the onces that you get off ebay you will throw a CEL cause there is no catalyst in it(its just a straight pipe). its ok for OBD1 cars cause they only have one o2 sensor. the OBD2 cars have one before the cat and after the cat. its the o2 sensor that is after the cat that is giving you the code. so just go check out the cat and make sure you have a real high flow or just get an OeM. hope this helped

 

https://honda-tech.com/zerothread/1171263

 

To tell the truth I am not sure. It was given to me from a friend. I know he uses ebay alot, so I am guessing the ebay hi-flow cat. It has baffles on the sides, but I am just gonna say its the ebay one. This is the cat underneath the car, not the one on the exhaust manifold. If that little connector got loose, would that cause the problem? And another dumb question..the gasket that sits between the cat and midpipe, is well pretty much toast. I didnt have enought time to run down to the store to pick one up. Would that air leaking out cause this?