What is trouble code P1131-ford-Taurus?

The trouble code P1131 for a Ford Taurus indicates a problem with the air-fuel ratio sensor, specifically that the sensor is reporting a lean condition (too much air, not enough fuel) in the engine's exhaust. This can be caused by various issues, such as a vacuum leak, a malfunctioning fuel injector, or problems with the mass airflow sensor. Addressing the underlying cause is essential to ensure proper engine performance and efficiency. It's advisable to perform a thorough diagnostic to pinpoint the exact issue.