P0171 is a generic OBD-II trouble code that means: Fuel System (Bank 1) – System Too Lean. You can drive carefully for a short time, but have it fixed promptly. Ignoring it can reduce performance and damage other parts.
What does P0171 mean?
P0171 is a generic OBD-II trouble code that means: Fuel System (Bank 1) – System Too Lean. The engine control module (ECM) stores this code when it detects a fault related to: Fuel System (Bank 1).
Can I still drive?
You can drive carefully for a short time, but have it fixed promptly. Ignoring it can reduce performance and damage other parts.
Symptoms
- Check engine light is on
- Rough or unstable idle
- Hesitation or jerking when accelerating
- Loss of power
- Engine stalls
Common causes
- Vacuum or intake air leak
- Dirty or contaminated MAF sensor
- Low fuel pressure (weak fuel pump or clogged fuel filter)
- Clogged or leaking fuel injector
- Exhaust leak before the sensor
How to fix it
- Read all stored codes and freeze-frame data with an OBD-II scanner
- Check for vacuum and intake leaks (a smoke test is the fastest method)
- Clean the MAF sensor with dedicated MAF cleaner spray
- Measure fuel pressure with a gauge
- Check for exhaust leaks upstream of the sensor
- Clear the code and road-test the car to confirm the repair
Frequently asked questions
What does code P0171 mean?
P0171 is a generic OBD-II trouble code that means: Fuel System (Bank 1) – System Too Lean. The engine control module (ECM) stores this code when it detects a fault related to: Fuel System (Bank 1).
What causes code P0171?
The most common causes are: Vacuum or intake air leak; Dirty or contaminated MAF sensor; Low fuel pressure (weak fuel pump or clogged fuel filter); Clogged or leaking fuel injector.
How do I fix code P0171?
Start with these steps: Read all stored codes and freeze-frame data with an OBD-II scanner; Check for vacuum and intake leaks (a smoke test is the fastest method); Clean the MAF sensor with dedicated MAF cleaner spray; Measure fuel pressure with a gauge.
Is it safe to drive with code P0171?
Severity: Medium. You can drive carefully for a short time, but have it fixed promptly. Ignoring it can reduce performance and damage other parts.