P0171 Nissan-after testing, the car is NOT running lean, so Whats causing the code to show up?

Question

After extensive testing, the car in fact is NOT running lean as the code claims. What could make this code appear? Maybe a sensor? Please help!

Answer 1

Hi there,

I am not sure how you would know the car is not running lean, but a faulty front O2 sensor can cause a lean condition or read lean. Sometimes the rear sensor could be reporting it as well, but normally if the engine is running fine, it's an issue with the front AF sensor.