P0109 - Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
A Manifold Absolute Pressure Sensor (MAP) is used to measure pressure in the intake manifold. With the ignition on and engine not running this sensor can be used as a barometric pressure sensor to measure atmospheric pressure.
Fault Code Explained
The ECM has detected the sensor value that is changing in a manner not consistent with the operating conditions, the value may be going outside of normal operating parameters.
If possible use a diagnostic computer to read live data to compare sensor values with actual values.Carry out wiring and sensor output tests on the faulty circuit