P0109 Manifold absolute pressure / atmospheric pressure sensor – break
Symptoms of a general failure code P0109
- Possible increased fuel consumption.
- A difficult start is possible.
- Reduced engine power.
- jerking when accelerating.
- The engine works richly
- The engine is not idling
- The engine shoots into the exhaust pipe
- Interrupted engine under load or at idle.
Causes of general OBD2 code P0109
- Broken power, signal or ground wire
- Leak in the intake unmeasured air entering the inlet duct through leaking gaskets or cracked / displaced / degraded hoses / vacuum hoses or inlet ducts
- Fuel vapor valve defective (open all the time)
- Faulty MAP / MAF / BARO / TPS sensors.
- Clogged catalyst (catalysts).
- Loss of ground contact with the MAP sensor.
- Loss of ground contact with the TPS sensor.
- ECM failure, although this is rare.
Codes associated with P0109
- P0106 - Refers to the manifold absolute range / pressure in the barometric pressure circuit / performance problem
- P0107 – Refers to the low level of the manifold absolute pressure circuit / barometric pressure
- P0108 – Refers to high manifold absolute pressure circuit / barometric pressure
- P0109 – Refers to an intermittent manifold absolute pressure / barometric pressure
DTC Description P0109 General
The MAP sensor (absolute pressure in the intake manifold) is part of the fuel management system. Reacts to pressure changes in the engine’s intake manifold. The ECM (Engine Control Module) constantly monitors the MAP sensor to correctly control the engine. Changes in engine load require a change in the amount of fuel injected, timing of the ignition system, etc. The engine under load has more manifold pressure (or less vacuum) than the engine running at idle. As the load changes, the MAP sensor voltage signal to the ECM changes accordingly. However, to check the MAP sensor operation, the ECM observes other sensors to check that the MAP sensor is working properly. For example, the ECM compares the TPS signal (throttle position sensor) with the MAP signal to check that the MAP signal is not ‘hanging’. If the ECM does not see the MAP sensor voltage change immediately after the throttle sensor signal changes, it knows there is a problem with the MAP sensor and sets P0109. Or, if the PCM notices that the TPS indicates that the engine is under load, but the MAP signal indicates that the engine is “accelerating”, it again knows that there is a problem with the MAP or TPS sensor and sets P0109.