Manifold Pressure/Vacuum Sensor: Description and Operation

The MAP sensor is an absolute pressure sensor used to monitor the EGR/EPR valve vacuum circuit. Voltage signals from the MAP sensor are transmitted to the ECM and used to calculate the EGR solenoid dwell period. In addition, MAP sensor signals are compared to the calculated dwell period signal, and if a difference exists, the ECM illuminates the ``Check Engine'' lamp to signal a system malfunction.