p0171
Moderate
GMC · Trucks
System Too Lean Bank 1
Quick Answer
Error code P0171 on your GMC Trucks means: System Too Lean Bank 1. This is usually fixable — see the step-by-step guide below.
Affected Models
Likely Causes
How to Fix It
1
Connect diagnostic scanner and read fault codes
2
Inspect oxygen sensor connector and wiring
3
Check fuel pressure with fuel pressure gauge
4
Perform visual inspection of intake for leaks
5
Clear code and test drive to confirm
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Oxygen sensor
Fuel injector
Air intake gasket
MAF sensor
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