P0171 on Ford: 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 Ford
Lean codes on Ford vehicles commonly trace to a dirty MAF sensor, cracked PCV hoses, and intake manifold gasket leaks on older V8 engines. When P0171 and P0174 show together, look for a shared leak or the MAF.
On some older Ford V8 trucks, intake gaskets were known to leak air and occasionally coolant, so watch the coolant level too.
Most likely causes on Ford vehicles
- Dirty MAF sensor
- Cracked PCV or vacuum hose
- Intake manifold gasket
- Weak fuel pump
Order reflects cost and likelihood in general; your vehicle may differ. Confirm with testing before buying parts.
Ford specific tips
- Clean the MAF sensor with dedicated cleaner first; it is cheap.
- A smoke test quickly finds hose and gasket leaks.
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 Ford 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 Ford fix” videos.
Repair manuals
Step-by-step service manuals for Ford with torque specs and wiring diagrams:
Haynes manuals for Ford Chilton manuals
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Check Ford recalls
Enter your VIN at the NHTSA recall lookup before paying for repairs.
FAQ
Can a Ford P0171 be fixed for under $50?
Often yes, when it is a hose or a dirty MAF.
Why both P0171 and P0174 on my Ford?
Both banks are lean, which points to a shared cause like the MAF or a central vacuum leak.
Read the full P0171 guide or more Ford check engine notes.