The P0171 code on a 2004 Lincoln LS V8 indicates that the engine control module (ECM) has detected a lean air-fuel mixture in the engine's first bank of cylinders. This means that there is too much air and not enough fuel in the mixture, causing the engine to run lean.
Possible Causes:
- Vacuum leak
- Faulty oxygen sensor
- Faulty fuel injector
- Faulty mass air flow (MAF) sensor
- Faulty fuel pressure regulator
- Leaking fuel injector
Symptoms:
- Engine may run rough or misfire
- Engine may stall
- Decreased fuel efficiency
- Check engine light is on
Diagnosis:
To diagnose the P0171 code, a mechanic will need to use a diagnostic tool to scan the engine control module (ECM) for trouble codes. The mechanic will also need to perform a visual inspection of the engine and check the oxygen sensor, fuel injector, MAF sensor, and fuel pressure regulator for proper operation.
Repair:
The repair for the P0171 code will depend on the cause of the problem. Common repairs include replacing the faulty oxygen sensor, fuel injector, MAF sensor, or fuel pressure regulator. The mechanic may also need to perform a smoke test to find any vacuum leaks.
