GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hi Im David thanks for visiting the site. allow me a few moments to pull up some information for you. thanks
P0171 refers to the fuel trim system being lean. Possible causes could be water in the fuel, too much alcohol in the fuel, a clogged fuel injector and/or a weak fuel pump. check out these TSB's on your vehicle.
checking in to see how its going
were you able to have it taken care of?