THE CHECK ENGINE LIGHT CAME ON AND I TOOK IT TO ...
2003 Hummer H2
The check engine light came on and I took it to Auto Zone and two codes came up PO171 and PO174 System too Lean (Bank 1) what does that mean?
Monday, December 31st, 2012 AT 8:10 PM
It means just that. The system is extremely lean for some reason and the computer has reached it's limit in being able to compensate for it. Check carefully for vacuum leaks and any leaks in the intake between the MAF and throttle body.