Problem: The vehicle came in because the MIL was
on. The tech pulled a P0171 (Fuel System Too Lean – Bank 1) DTC.
Details: First, the tech connected a scan tool
and checked the long and short fuel trims. The sum of both
equaled +30% at idle. The reading did not improve or change at
any RPM. He checked for vacuum leaks and found none.
Because the fuel trims were not worse at heavy load, he
suspected that the fuel pressure and volume was correct but
checked it anyway. The fuel pressure and volume was at
specification at all engine speeds. Next, the tech checked the
Mass Air Flow meter (MAF) PID and found it to be low (2.6 g/s
Confirmed Repair: When he removed the MAF to
inspect it, he found a large bug inside it. He removed the bug,
cleaned the MAF and fuel trims returned to normal. After
clearing the DTC, the vehicle was fixed!