I hope I did anyhow. I just bought a 00 si. The second week I had it the engine light came on. I went to O'rielly's Auto and used their Auto x-ray. I got the code p0240. It pretty much means that the secondary 02 sensor is failing. So, being cheap, I got one off eba* for 27 bones. I put it on and cleared the ecu. I drove for about 20 mins. and the engine light came back on. I went back to the parts store to scan the ecu. I got the code p0141. It means 02 heater circuit problem. I was wondering about maybe having a bad cat so I called my local muffler shop. I explained my problem and the guy says that he does't really think it's the cat. He asked me if the 02 sensor I bought was the kind that you had to splice together. I said it was. He suggested that I got one with a plug like o.e.m. He said the Bosche was good and gave me the part number. I ordered one and switched them out. At the same time I read on a forum about the spark plug defouler trick, so I did that too. Well,people, it worked. I saved myself a trip to the mechanic. I hope this helps anybody

 

What and how does the plug defowler work I also have a CEL heat sensor o2 fault is there a way to trick the ecu about the o2 sensor.