Throwing Codes P1151 & P0171

[Ferocious]

So my car is now throwing codes P1151 (Lack of HO2S-21 Switch, Sensor Indicates Lean) and P0171 (System Too Lean (Bank 1)). Could a bad upstream 02 sensor be the cause of this?

 

[borlakid96]

Don't shoot the messenger. The sensor is telling you what its Lean. Vacuum leak? Exhaust leak?

 

[Ferocious]

nope and nope.


Tested voltage and my upstream sensor on bank 2 isn't working.
Guess that may be the issue.

 

[Shifty Powers]

that could be a cause.. otherwise yes a leak somewhere. But if it isnt getting any voltage.. i would start there for sure