Other than checking for a worn grommet and loose electrical connections, the only service possible is unit replacement, if the diagnosis shows the sensor to be faulty.
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
Important: Lightly coat the MAP sensor seal and intake manifold with a small amount of GM lubricant P/N 9985662 or equivalent may be used on the MAP sensor seal and intake manifold only, to aid in installation.
Tighten
Tighten the nut to 25 N·m(19 lb ft).
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.