Manifold Absolute Pressure (MAP) Sensor Inspection and Replacement

INSPECTION
PROCEDURE

1. The MAP sensor monitors changes in intake manifold vacuum caused by variations in engine speed and engine load, and converts this information into a voltage signal. The PCM uses the signal from the MAP sensor to adjust ignition timing. The sensor output voltage varies from 1.0 ÷ 1.5 V with the throttle valve fully closed (high vacuum) to 4.0 ÷ 4.5 V with the throttle valve fully open (low vacuum), and may vary slightly depending on vehicle altitude above sea level. The MAP sensor is mounted on the throttle body. Sensor failure results in code P0107 or P0108 being stored in the self-diagnostic memory.

2. Measure the reference voltage supplied to the sensor from the PCM. Disconnect the wiring harness connector and connect a voltmeter between the REF (+) and GND (-) terminals of the connector. With the ignition on, the meter should read approximately 5.0 V. No reference signal indicates an open circuit in the PCM circuit or a faulty module.

3. Check the sensor signal voltage with the engine off. Connect a voltmeter between the SIG (+) and GND (-) terminals of the sensor connector. With the ignition on, the signal voltage should be within the range of 2.5 ÷ 3.5 V.
4. Now check sensor operation with the engine running. Start the engine and observe the voltmeter as engine speed increases from idle. The signal voltage should increase as vacuum decreases. At idle, vacuum is at its maximum and the signal voltage should not rise above 0.5 ÷ 1.5 V. As engine speed increases, vacuum decreases, which should lead to a decrease in the measured signal voltage.

Changes in intake manifold vacuum can be monitored using a vacuum gauge. With the throttle fully open, manifold pressure may equal atmospheric pressure. For more detailed information on vacuum checks, refer to the Engine General Information and Engine Overhaul section of the Engine group.
5. If the test results are unsatisfactory, replace the sensor.

REPLACEMENT
PROCEDURE

1. Disconnect the negative battery cable.

If the vehicle is equipped with an anti-theft radio, make sure you have the correct code for activating the audio system before disconnecting the battery!

2. Disconnect the wiring harness from the MAP sensor.

3. Remove the mounting screws and remove the sensor from the throttle body.

4. Installation is the reverse of removal.