I went to the Autozone today to borrow the OBD II sensor to see what happened with my check engine light. It says "O2 Sensor too lean (bank 1)". What does it mean? Is there anyone experienced this? I have Tomei manifold, O2 housing and dp, Megan test pipe and trust Ti-R (no cat) on my car. I have a DIY CEL fix on the test pipe. The first time I put on the CEL fix the light went off but on again after a few minutes. Any input would be appreciated.

 

could mean you have a maf sensor problem or a dirty air filter

 

I think my filter is not that dirty. What is a a maf sensor problem ?

 

Front O2 sensor is bad

 

U mean the one plug into the O2 housing, rite? But how come it suddenly went bad since there was no engine light before I put the aftermarket parts on. After I put the manifold, O2 and the test pipe on, the engine light goes on. I thought it was the test pipe so I put the CEL fix on. My car is only 13k miles. The problem is I got the ref ticket before and put everything back to stock and the light went off.

 

Check the harness first See if there is any sign of wire damaged, try to unplug and plug it back. Sensors are no difference from bulbs. Sometimes it will last and sometimes it will go bad fast.

 

Ok, if this is the case, where can I get a replacement for cheap? I don't want to spend another $200 for a sensor. Also, the more important thing is does it affect the performance of the car? My car had been tuned under this situation.

 

http://sparkplugs.com/more_info.asp?...1446&pid=17860

 

Thanks for ur help. But are the front O2 sensor same as the rear one? If I don't change the sensor, does it affect the performance or no?

 

when you took your car in to get inspected did you only change your downpipe,testpipe, greddy exhuast back to stock? or did you also put the stock manifold,o2 housing back on too?

 

Try cleaning your maf sensor with some electric contact cleaning spray or isopropyl alcohol. It could be an easy fix if your maf sensor is dirty. Happened to me a few times in my other car.

 

NO, the front and the rear sensors are different. The front one is what is causing the CEL to go off. Trust me its on its way out, you will start to notice worse and worse gas mileage every fillup. The link a few posts up is what I just put on yesterday and works like a charm. They should have them in stock now since I had to wait 2 weeks to get mine.

 

I also put back my stock manifold and O2 housing.

 

So, do I have to tune the car again or I am good?

 

No tune is necessary. Your car uses that front o2 sensor to adjust it's afr's. If it's going bad it's telling the ecu a bunch of crap information resulting in poor fuel economy and probably running like crap. Check the wiring, but most likely a new one is in your future.