P0171 — System Too Lean (Bank 1)
Reviewed1 source
1 source
- Official data (NHTSA)official_feed
What P0171 means
Caution — monitor closely
Long-term fuel trim has gone positive beyond the allowed range — the ECU keeps adding fuel to compensate for excess air or insufficient gasoline.
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General information, not a diagnosis or repair instruction. Always confirm with a qualified mechanic for your specific vehicle.
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What does the P0171 code mean?
Watch on YouTubeCommon causes
- Vacuum leak in the intake system
- Vacuum leak downstream of the MAF sensor
- Weak fuel delivery
- Dirty or faulty MAF sensor
Symptoms
- Rough or high idle
- Повышенный расход топлива
- Loss of power under load
- Fluctuating idle RPM
- Reduced fuel economy
- Hesitation on acceleration
- Check-engine light with P0171 stored
- Hissing sound near the intake at idle
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