General Motors, commonly referred to as GM, manufactures many types of vehicles that are sold under many GM name brands, such as Chevrolet and Pontiac. All GM vehicle engines and components are designed and positioned similarly. The manifold absolute pressure sensor is sometimes referred to as the barometric pressure sensor. The sensor measures the atmosphere's barometric pressure and sends this information to the powertrain control module (PCM). The PCM uses this information to adjust the air-to-fuel ratio to make up for changes in the air pressure due to weather or the specific elevation. It's important to replace a faulty sensor to ensure your engine runs efficiently.
Open the hood of the GM vehicle. If the vehicle was recently driven, allow a half hour for the engine to cool down.
Locate the barometric, or MAP, sensor. The sensor is found on the top of the engine to the left of the EGR valve on 3.4 and 3.1-liter GM engines. On larger engines, such as the 4.2-liter GM engine, the sensor is found directly to the left of the Powertrain control module on the driver side of the vehicle. The sensor is a small black box with a three-wire harness coming out of the side. Refer to your repair manual for a diagram, if needed.
Squeeze the sides of the wire harness and pull straight out from the sensor. Remove the two to four screws that secure the sensor in place. The number of screws can vary from vehicle model. Use a Torx #15 with driver to remove the screws. Lift the sensor off the mount and discard.
Align the replacement sensor and place on the mount. Replace the four screws and tighten. The sensor is now secured to the vehicle. Plug the wire harness into the new sensor until you hear it click into place. The sensor is now ready for use. Close the hood of your GM vehicle.
