O2 sensor voltage and STFT

[Brandoe91]

I was looking at some data on a obdII scanner and something doesn't seem right. Maybe someone help me understand if the data below is normal.

My o2 sensor voltage seems low at idle. I read somewhere that said .45V is the norm.


Maybe the sensors are o2 sensor are bad and is the cause of my P0171 lean code.


And are short term fuel trims suppose to be at 0 at idle. It also never moved from while revving in neutral


Any help Appreciated

[1gSE]

http://www.autodiagnosticsandpublishing ... esting.htm

IIRC you want your STFT as close to zero as possible

[Brandoe91]

Thanks 1gse.Now I just have to figure out what is causing the car to run lean. I already check air intake and vacuum lines for leaks. I will do some more eliminating when I get break from school next week.

[1gSE]

are you sc'd? Have you recently done any work on the intake side? Last time I pulled the blower, the guy helping me put the throttle body gasket on wrong and it threw a lean code....plus the afr gauge was reading like...17+ and the car did run very well

[Brandoe91]

Nope still haven't installed it. I did however install an injen intake and you already know the headers and catback. The clamp for the coupler on the intake was a little loose, so i tightened it and reset the code.I think have an exhaust leak because those obx gaskets were sh**ty.

[1gSE]

Hmm...I think if it's on the header flange that could probably cause a lean code

[Brandoe91]

Probably, since I have a a nut missing on the front flange and one or 2 on the rear flange.