what does code P1131 mean?

Answer

You may have a bad oxygen sensor - the one located before the catalytic converter. If you have a V engine, look for the one connected to the side where cylinder one is located. Also, other faults can set this code (lean-condition): a faulty MAF sensor, a vacuum leak, bad fuel system pressure, or a leaking fuel injector.

Updated on April 11, 2018

Original Article:

What it Means When a Check Engine Light is On or Flashing
By Dan Ferrell
working