Manifold Absolute Pressure/Barometric Pressure Circuit High Input
Our emissions expert has put together the following information about the P0108 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
OBD II Fault Code
- OBD II P0108
Fault Code Definition
The Manifold Absolute Pressure Sensor/Barometric Pressure Sensor measures the rise and fall of the air pressure inside the Intake Manifold. This provides critical data needed for the Powertrain Control Module (PCM) to control the Air Fuel Ratio, the Ignition Spark Timing, and many components of the Emissions Control Systems. The Manifold Absolute Pressure/Barometric Pressure Sensor converts the Intake Manifold air pressure into a voltage that is high when the Intake Manifold air pressure is high and low when the Intake Manifold air pressure drops to a vacuum. The P0108 code indicates a high voltage input from the Manifold Absolute Pressure Sensor/Barometric Pressure Sensor to the Powertrain Control Module.
Symptoms
- Check Engine Light will illuminate
- In many cases, no abnormal symptoms may be noticed
- In some cases, the engine may be hard starting and/or get poor fuel economy
- In some cases, noticeably poor engine performance may occur
Common Problems That Trigger the P0108 Code
- Manifold Absolute Pressure Sensor/Barometric Pressure Sensor is defective
- Intake Manifold vacuum leaks
- Faulty or corroded Manifold Absolute Pressure Sensor/Barometric Pressure wiring or connections
Common Misdiagnoses
- Manifold Absolute Pressure Sensor/Barometric Pressure Sensor is replaced when the real cause is an Intake Manifold vacuum leak
- Manifold Absolute Pressure Sensor/Barometric Pressure Sensor is replaced when the real cause is a stuck-open EGR Valve
- Manifold Absolute Pressure Sensor/Barometric Pressure Sensor is replaced when the real problem is a defective Idle Air Control Motor, which causes a very low engine idle
