P0171 Most Common Cause W/O Driveability Issue

[Dakcbeast]

Engine light came on. Odb2 shows 0171. No noticeable driveability issues. What's the most common cause? Thanks!

 

[PNWYukon]

P0171 code possible causes​

• Intake air leaks
• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Faulty Mass Air Flow (MAF) sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection

 

[Dakcbeast]

P0171 code possible causes​

• Intake air leaks
• Faulty front heated oxygen sensor
• Ignition misfiring
• Faulty fuel injectors
• Exhaust gas leaks
• Incorrect fuel pressure
• Lack of fuel
• Faulty Mass Air Flow (MAF) sensor
• Incorrect Positive Crankcase Ventilation (PCV) hose connection

Thanks man. Just had the cats replaced and they left a slight audible
leak...

 

[PNWYukon]

Get that buttoned up and you should be good to go.

 

[Richard Blakely]

Anyone ever hear of a pcm replacement causing an erroneous P0171 trouble code? Ever since my computer was replaced (for another reason). P0171 shows up with check engine light. Any troubleshooting done by qualified techs have come back with no problem found.

 

[Fless]

SWAG: check your PCM connectors by disconnecting them, inspecting the pins and sockets, and reconnect. Maybe it has a connection issue there.

Disconnect battery before doing that, and also touch the cable ends together (while disconnected) to reset memory.

 

[Richard Blakely]

Anyone ever hear of a pcm replacement causing an erroneous P0171 trouble code? Ever since my computer was replaced (for another reason). P0171 shows up with check engine light. Any troubleshooting done by qualified techs have come back with no problem found.

Update to P0171 trouble code. Believe I got it resolved by replacing purge valve. I know code doesn’t point to this but since I replaced it and cleared codes (battery disconnected for 10 minutes), no check engine light and gas mileage is improved, runs great as well.