P0171 on Chevrolet: System Too Lean (Bank 1)
Severity: 2 of 4
Usually drivable in the short term if the car runs well and the light is steady. Get it fixed soon, because a lean engine can misfire and run hot. If you get misfire codes or the light flashes, park it.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0171 usually means on a Chevrolet
On older GM 3.1 and 3.4 liter V6 engines, intake manifold gasket leaks are widely documented and can cause both lean codes and coolant loss. Newer Chevrolet engines more often show lean codes from a dirty MAF, PCV problems, or vacuum hose leaks.
On high mileage trucks, a weak fuel pump can also cause lean codes, especially under load.
Most likely causes on Chevrolet vehicles
- Vacuum or PCV hose leak
- Dirty MAF sensor
- Intake manifold gasket (older V6)
- Weak fuel pump
Order reflects cost and likelihood in general; your vehicle may differ. Confirm with testing before buying parts.
Chevrolet specific tips
- On older V6 engines, check for coolant loss and a sweet smell.
- Fuel pressure testing is worthwhile on high mileage trucks.
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Vacuum or PCV hose | $10 to $80 | 0.3 to 1.0 h | $10 + 0.3 × $110 = $43 $80 + 1.0 × $190 = $270 |
| MAF sensor cleaning or replacement | $10 to $250 | 0.2 to 0.5 h | $10 + 0.2 × $110 = $32 $250 + 0.5 × $190 = $345 |
| Intake manifold gasket | $20 to $150 | 1.0 to 4.0 h | $20 + 1.0 × $110 = $130 $150 + 4.0 × $190 = $910 |
| Fuel pump | $120 to $600 | 1.5 to 3.5 h | $120 + 1.5 × $110 = $285 $600 + 3.5 × $190 = $1,265 |
Costs are generic for this code; parts and labor on some Chevrolet models may run higher.
Watch a repair video
System Too Lean: Code P0171 or P0174 (1A Auto). Third-party video, loads from YouTube (privacy-enhanced mode) only when you press play. Procedures vary by vehicle. Search YouTube for “P0171 Chevrolet fix” videos.
Repair manuals
Step-by-step service manuals for Chevrolet with torque specs and wiring diagrams:
Haynes manuals for Chevrolet Chilton manuals
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Check Chevrolet recalls
Enter your VIN at the NHTSA recall lookup before paying for repairs.
FAQ
Can an intake gasket leak damage my engine?
If coolant leaks internally, it can contaminate oil. Get it checked quickly.
Is the MAF a common culprit?
Yes, and cleaning is a cheap first step.
Read the full P0171 guide or more Chevrolet check engine notes.