DTC P1129: Manifold Absolute Pressure (MAP) Sensor Signal Higher Than Expected: General Description

The manifold absolute pressure (MAP) sensor senses manifold absolute pressure (vacuum) and converts it into electrical signals. The MAP sensor outputs low signal voltage at high vacuum (throttle valve closed) and high signal voltage at low vacuum (throttle valve wide open). The engine control module (ECM)/powertrain control module (PCM) compares a predetermined MAP value at a given throttle position and manifold absolute pressure to the output voltage value of the MAP sensor. If the MAP sensor outputs high voltage during fuel cut-off operation for deceleration with the throttle valve fully closed, which should make the manifold absolute pressure lower, the ECM/PCM detects a malfunction and stores a DTC.