How do you fix a obd 2 code 1131 on a 97 cougar 3.8 liter engine?

Answer 1

Consider:

Check for, vacuum leak or loose hose at throttle body or MAF sensor. Favuum leaks are common and may present a hissing noise. If you can spray carb cleaner near intake gasket, on vacuum hose, or intake hose someplace where it changes the sound of the engine you have found your leak.

Check for an exhaust leak. Exhaust leaks have a very distinctive sound.

Check for a misfire. Your car shakes.

Check for faulty or damaged MAF sensor:

-Runs better with MAF sensor unplugged or:

-Banging MAF sensor with your fist whilke engine idling makes a change in sound of engine or:

-Remove MAF sensor and look at the wire. If it isn't clean and shiny silver color, it is contaminated. Clean or replace as needed.

Bad oxygen sensor upstream (before cat) bank one. Bank one is the side with cylinder #1.

Water or extreme temperatures affecting sensor operation. Remove water or wait for weather to improve or replace sensor.

XXXXXXXXXXXXXXX Answer XXXXXXXXXXXXXXXXXX The question referred to a code p1131 which is upsteam oxygen sensor lean. I personally would change the PCV Valve with one from NAPA. A stuck open PCV Valve can draw in unmetered air and set the code.jd1909