All codes › P0171
P0171: System Too Lean (Bank 1)
What it means
Bank 1 is running lean (too much air or too little fuel), and the computer has maxed out its fuel correction.
Severity: Medium Lean running can cause hesitation and, over time, misfires.
Common causes
- Vacuum leak (cracked hose, intake gasket, PCV)
- Dirty MAF sensor
- Weak fuel pump or clogged filter
- Clogged injectors
- Exhaust leak before O2 sensor
Most common causes first. Exact causes vary by make, model and engine.
Can I fix it myself?
Sometimes DIY. Listen for vacuum hisses and clean the MAF; check fuel trims on a scan tool.
Repair cost
SEEDED ESTIMATE Roughly $110–$470
Most likely repair: mass air flow sensor. Diagnosis fees, taxes and other causes are not included.
| Line | Low | High | Basis |
|---|---|---|---|
| Mass air flow sensor | $64 | $226 | Typical listed retail range, source (one $568 outlier excluded) |
| Labor 0.5–1.5 hr | $50 | $240 | $100–$160/hr, shop survey |
⚠️ This is an editorial placeholder range for this type of repair. It is not based on real invoices or licensed pricing data yet. Real ranges will appear here once enough reader invoices for P0171 are verified.
Verified reader invoices for P0171: 0. Share your repair bill to help build real costs.
Tools that can read P0171
- ScanFixAI: Pro $29.99/mo or $249.99/yr
- OBDAI: Annual PRO bundle $299
- BlueDriver Pro Next-Gen: $119.95 list ($99.95 sale seen)
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