P0171Severity: Medium
P0171 – System Too Lean (Bank 1)
The fuel mixture is too lean (too much air / too little fuel).
What it means
Despite the ECU adding fuel to balance bank 1, the mixture stays lean. The most common causes are intake/vacuum leaks or a dirty MAF sensor.
Symptoms
- Rough idle
- Loss of power
- Misfire
- Increased fuel use
Common causes
- Intake/vacuum leak
- Dirty MAF sensor
- Weak fuel pressure/pump
- Clogged injector
- PCV leak
With AutoMulti
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Frequently asked questions
What does trouble code P0171 mean?
P0171 – System Too Lean (Bank 1). Despite the ECU adding fuel to balance bank 1, the mixture stays lean. The most common causes are intake/vacuum leaks or a dirty MAF sensor.
Can I drive with a P0171 code?
You can usually drive short distances, but it's best to have it checked before it gets worse.