Manifold Pressure/Vacuum Sensor: Testing and Inspection

DTC 31 Diagnostic Chart:

MAP Sensor Circuit:

Component Failure Conditions
DTC 31 will set if either of the following conditions are met for at least 0.5 seconds:

(1) Voltage input at the PCM indicates very low manifold pressure.

(2) Voltage input at the PCM indicates very high manifold pressure.

Test Description:
Numbers below refer to circled numbers on the diagnostic chart.

1. This checks for an open or short to ground in the YEL wire between the PCM and MAP sensor.

2. This checks for an open in the LT GRN/RED wire between the PCM and MAP sensor.

3. This checks for an open in the BRN wire between the PCM and MAP sensor, and for a faulty PCM or MAP sensor.

Diagnostic Aids:
If DTCs 22, 24 and 41 are also set, problem is in sensor ground circuit.
An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect hamess connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.