OBD-II TROUBLE CODE GUIDE
P0171: System Too Lean — Bank 1
The engine computer is adding excessive fuel to compensate for a lean mixture.
What P0171 means
The engine computer is adding excessive fuel to compensate for a lean mixture.
Common possible causes
- Vacuum or intake leak
- Incorrect airflow measurement
- Low fuel pressure or an exhaust leak
What to check first
Record all stored and pending codes and freeze-frame data before clearing anything. Inspect relevant wiring, connectors, hoses, fluid levels, and obvious damage. Use vehicle-specific service information and test the affected system before purchasing parts.
A code is not a parts order. Several faults can create the same code, and replacing the component named in a code description may not correct the underlying problem.
Look up P0171 for my vehicle