Diagnostic Aids

With ignition on and engine off, manifold pressure is equal to atmospheric pressure with signal voltage being high. This information is used by PCM as an indication of vehicle altitude. Comparison of this reading with a known good vehicle with the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same plus or minus .4 volt.

DTC 33 will set if an open is present in sensor ground circuit, or if EGR control pressure/BARO signal circuit is shorted to voltage or to 5-volt reference circuit. Ensure electrical connectors remain securely fastened. Refer to EGR CONTROL PRESSURE/BARO SENSOR OUTPUT CHECK chart (see link below) for further diagnosis.

• EGR CONTROL PRESSURE/BARO SENSOR OUTPUT CHECK 

Fig 1: DTC 33 Schematic ("G" Series) EGR Control Pressure/Baro Sensor Circuit High (Low Vacuum)

Fig 2: DTC 33 Schematic ("P" Series) EGR Control Pressure/Baro Sensor Circuit High (Low Vacuum)

Fig 3: DTC 33 Flow Chart (All Models) EGR Control Pressure/Baro Sensor Circuit High (Low Vacuum)