Jim Grant's Tech Tips
‘98 Ford Mustang, Unknown Fault Code
Q: I was recently given a ‘98 Ford Mustang with a 3.8 v6. The check engine light was on and runs rough. At the local dealer, a tech used an OBDII scanner and got this code and no one there knew what it referred to. The code shown is P1131 fuel air metering fault. Unsure of the quality of tech knowledge and not wanting to spend more money on more diagnostic for I am currently on workman’s comp for a back injury. I’m trying to get all the information so I can find a qualified equipped shop to have repaired.
- David J.
A: The code you’re reporting is for a lack of the oxygen sensor #1 on bank #1 switching and indicating a lean condition. Also, this code refers or sends the tech to code P2195 for diagnosis. This code means that the O2 sensor signal is stuck lean. Because you are reporting that the engine is running rough and the code is for only one side of the engine, I’m inclined to believe that you may have a vacuum leak or something on that line for a problem. It is possible that the O2 sensor has failed but that is an easy item to prove when diagnosing. I do find it odd that the dealer tech was not able to tell you what this code was or provide a generalization for the code. Most of the Ford Techs I know can tell you what that code means from memory. This leads me to believe that the person checking and reporting the code was not what we would call a real tech.