Code 31, Map Sensor, Open Or Shorted Circuit: Notes

MAP sensor responds to changes in manifold pressure (vacuum). MAP sensor consists of a semi-conductor type pressure converting element which converts a pressure change into an electrical change and an electrical circuit which amplifies and corrects electrical change. ECM applies 5 volts to MAP sensor.

Changes in pressure, engine load and RPM are converted into voltage input monitored by ECM. A low voltage input at ECM indicates low manifold pressure and a high voltage input at ECM indicates high manifold pressure.

Code 31 will set if voltage input at ECM indicates either very low or very high manifold pressure for at least .5 second.

1. Checks for open or short to ground in Yellow wire between ECM and MAP sensor.
2. Checks for open in Light Green/Red wire between ECM and MAP sensor.
3. Checks for open in Brown wire between ECM and MAP sensor, and a faulty ECM or MAP sensor.