P0171 Code: Meaning, Symptoms, Causes & Fixes
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Causes ranked by likelihood
| Cause | Likelihood | DIY difficulty |
|---|---|---|
| Vacuum leak — Cracked intake hose, bad PCV valve, or torn boot. Smoke-test the intake. | Most likely | 2/5 |
| Dirty MAF sensor — A $8 can of MAF cleaner fixes this in 5 minutes. | Possible | 2/5 |
| Weak fuel pump or clogged filter — Low fuel pressure starves the engine. | Possible | 2/5 |
| Failing fuel injector — Clogged or leaking injector skews the air/fuel mix. | Less likely | 2/5 |
| Bad oxygen sensor — Lazy upstream O2 reports incorrect mixture. | Less likely | 2/5 |
Symptoms of P0171
- Rough idle
- Hesitation on acceleration
- Check engine light
- Reduced power
How to diagnose P0171
- Confirm the code. Read P0171 with an OBD-II scanner and note the freeze-frame data (speed, temperature, load) recorded when it set.
- Check for companion codes. Look for other stored or pending codes such as P0174, P0101, P0420 — they often point to one shared root cause.
- Check: Vacuum leak. Cracked intake hose, bad PCV valve, or torn boot. Smoke-test the intake.
- Check: Dirty MAF sensor. A $8 can of MAF cleaner fixes this in 5 minutes.
- Check: Bad oxygen sensor. Lazy upstream O2 reports incorrect mixture.
- Check: Failing fuel injector. Clogged or leaking injector skews the air/fuel mix.
- Check: Weak fuel pump or clogged filter. Low fuel pressure starves the engine.
- Clear and verify. After the repair, clear the code and complete a full drive cycle to confirm P0171 does not return.
Can I drive with P0171?
Drive short distances only. A long-term lean condition can overheat and destroy your catalytic converter.
Related codes
Related symptoms
P0171 by vehicle
- P0171 on the Ford F-150
- P0171 on the Ford Escape
- P0171 on the Ford Explorer
- P0171 on the Ford Focus
- P0171 on the Ford Mustang
- P0171 on the Chevrolet Silverado
- P0171 on the Chevrolet Equinox
- P0171 on the Chevrolet Malibu
- P0171 on the Chevrolet Tahoe
- P0171 on the Chevrolet Traverse
- P0171 on the Chevrolet Cruze
- P0171 on the Toyota Camry
- P0171 on the Toyota Corolla
- P0171 on the Toyota RAV4
- P0171 on the Toyota Highlander
- P0171 on the Toyota Tacoma
- P0171 on the Toyota Prius
- P0171 on the Honda Civic
- P0171 on the Honda Accord
- P0171 on the Honda CR-V
- P0171 on the Honda Pilot
- P0171 on the Honda Odyssey
- P0171 on the Nissan Altima
- P0171 on the Nissan Rogue
- P0171 on the Nissan Sentra
- P0171 on the Jeep Grand Cherokee
- P0171 on the Jeep Wrangler
- P0171 on the Jeep Cherokee
- P0171 on the Hyundai Elantra
- P0171 on the Hyundai Sonata
- P0171 on the Hyundai Santa Fe
- P0171 on the Hyundai Tucson
- P0171 on the Kia Forte
- P0171 on the Kia Sorento
- P0171 on the Kia Sportage
- P0171 on the Kia Telluride
- P0171 on the Kia Optima
- P0171 on the Subaru Outback
- P0171 on the Subaru Forester
- P0171 on the GMC Sierra
- P0171 on the GMC Acadia
- P0171 on the Ram 1500
- P0171 on the Dodge Charger
- P0171 on the Volkswagen Jetta
- P0171 on the Mazda CX-5
- P0171 on the BMW 3 Series
- P0171 on the BMW X5
- P0171 on the Mercedes-Benz C-Class
Frequently asked questions
What does P0171 mean?
P0171 means system too lean (bank 1). P0171 means your engine is getting too much air or not enough fuel on Bank 1. The most common causes are a vacuum leak, dirty MAF sensor, or weak fuel pump.
Can I drive with code P0171?
Drive short distances only. A long-term lean condition can overheat and destroy your catalytic converter.
What is the most common cause of P0171?
Vacuum leak — Cracked intake hose, bad PCV valve, or torn boot. Smoke-test the intake.
What are the symptoms of P0171?
Rough idle, Hesitation on acceleration, Check engine light, Reduced power.
How much does it cost to fix P0171?
A typical shop repair range is $10–$800, depending on which cause it turns out to be. Cheaper causes such as bad oxygen sensor should be ruled out first.