2005 colorado p0171 bank 1 to lean

Keep getting p0171 code for bank 1 to lean. I’ve replaced both 02 sensors, purge valve, purge solenoid, vent valve, fuel pressure regulator, 2 coils, and gas cap. Still getting code p0171. Any suggestions?

Have you done any testing yet?

Fuel pressure test and smoke test come to mind

You also need to look at the freeze frame data

Under what conditions did the code set?


Under load?

I’ve got a few culprits in mind, but I think you need to start doing some testing

Do you at least have a scanner that shows live data?

Try cleaning the MAF sensor,

with MAF sensor cleaner.

The computer compares the signals it receives from the MAF to the O2 sensor.

If the MAF sensor element is contaminated where it doesn’t read the correct amount of air entering the engine, the computer thinks the engine is running lean because the O2 sensor detects more air than the MAF sensor.