Hey guys, the last 2 times I have plugged the tech 2 in and checked for trouble codes, I have been getting a code that says fuel trim lean bank 1. I do not know what this means, other than the fuel trim is lean, can someone clarify this info for me? Thanks a lot, Tommy

 

It's just following the OBD2 naming convention for the O2 sensors is all (which represents the primary input for the Rich/Lean DTCs)
The TECH2 also calls the O2 sensors Bank 1 Sensor 1 (pre cat) and Bank 1 Sensor 2 (post cat)
Wop

 

why would it be saying that? would it be because i tapped it to run my air/fuel gauge?

 

Is it a P0171??

 

yeah, i think so

 

no cel though

 

Well if no CEL then it was ust a history code- Clear it and see if it returns
Wop

 

ive cleared it twice now... i will check it again next weekend when i am home...

 

its a known problem with the cobalts, to have a p0171 code. according to gm there isnt a reflash or fix for it yet. but they are aware of the problem and theres a bulletin that says they are working on it. unless you have an intake. then thats another common problem

 

DTC P0171 = Fuel Trim System Lean.

 

Looking into this showed a few items for this

. Engine in closed loop status
. Engine coolant temp is between 19.4 and 248 degrees (F)
. Intake air temp is between 19.4 and 293 degrees (F)
. Manifold absolute pressure is between 2.2-14.5 psi
. Vehicle speed is less than 82 mph
. Engine speed is between 400 and 6,100 rpm
. Mass air flow is between 1-512 g/s
. Barometric pressure is greater than 10.4 PSI
. Fuel level is greater than 10 %

P0171 runs continuosly once the conditions have been met.