The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure (vacuum). The MAP sensor signal voltage to the PCM varies from below 2 volts at idle (high vacuum) to above 4 volts with the ignition switch ON , engine not running or at wide-open throttle (low vacuum).
If the PCM detects a voltage that is lower than the possible range of the MAP sensor, a Diagnostic Trouble Code (DTC) will be set. A signal voltage higher than the possible range of the sensor will also set a DTC. An intermittent low or high voltage will also set DTCs. The PCM can also detect a shifted MAP sensor. The PCM compares the MAP sensor signal to a calculated MAP based on throttle position and various engine load factors. If the PCM detects a MAP signal that varies excessively above or below the calculated value, a DTC will be set. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the PCM to automatically adjust for different altitudes.
Removal & Installation
- Disconnect the negative battery cable.
- Locate the MAP sensor and remove the retaining screws
- Detach the electrical connector.
- Remove the vacuum hose and lift the MAP sensor from the engine.
- Installation is reverse of the removal procedure.
As with most all engine control sensors used in your vehicle, a thorough and proper test can only be performed by a qualified technician using a scan tool to read the data stream from the PCM. There are a few items a non-professional should check before taking the vehicle to a qualified technician for diagnosis and repair.