Question

1999 Ford Escort 2.0L code P1131 how do I fix it? While idling in park Or drive it is very rough idle

Answer 1

Hi there,

This code is for the front O2 sensor, it means it's stuck lean. In other words the car can't make a fuel mixture properly and the sensor is telling it that. With the engine running poorly as well, you need to check for vacuum leaks. The most common on these is the pcv valve hose.