Diagnostic Trouble Code (DTC) P0108

Manifold Absolute Pressure Sensor High Voltage

 

 

What is the circuit like?

 

  • In unison with the Manifold Absolute Pressure (MAP) sensor, the engine control module (ECM) regulates the flow of fuel and the ignition timing.
  •  The MAP sensor which is metric pressure enables the ECM to make necessary adjustments for differing altitudes.
  • The output voltage of the MAP sensor changes with the change in the manifold pressure.
  • The intake manifold pressure created due to engine load (intake manifold vacuum) and the rpm changes is measured by the MAP sensor and transformed into voltage outputs.
  • The ECM notes the manifold pressure by keeping a vigil on the MAP sensor output voltage.
  • The MAP sensor directly receives a 5 volt-reference voltage sent to it by the ECM.
  • At idle, about 1.0 to 1.5 volts indicates a low-pressure (low voltage) output voltage.
  • At wide open throttle (WOT) about 4.5 to 4.8 volts indicates higher pressure (high voltage) output voltage.

 

 

When does DTC set?

Measures taken when DTC sets?

When will DTC clear?

1) When the engine is idling.

1) The Malfunction Indicator Lamp (MIL) will be seen glowing.

 

1) The MIL will cease after four consecutive ignition cycles in which the diagnostic operates flawlessly.

 

2) Engine speed is > 700rpm.

2) The ECM will record information of operating conditions at the time the diagnostic fails which will be stored in the Freeze Frame and Failure Records will prop.

 

2) A history DTC will clear after 40 successive warm-up cycles without a fault

3) No throttle position sensor (TPS) fail conditions are present.

3) A history DTC is stored.

3) The scan tool will unset all DTCs

4) The MAP is > 95kPA

4) The ECM replaces a fixed MAP.

4) Disconnecting the ECM battery link for more than 10 seconds

5) There is a high voltage condition.

5) The ECM uses TP to control the fuel delivery which the scan tool will not indicate at this stage.

 

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6) This DTC can be stored in "key-on" status.

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Diagnostic Assistance

  • The manifold pressure =atmospheric pressure when the ignition is ON and the engine is also switched OFF.
  • Under this circumstance the signal voltage will remain high.
  • The ECM makes use of this information as a reminder of vehicle altitude.
  • The reading obtained here can be cross checked with the reading of another car having the same sensor in common to verify and note the exactness of the suspected sensor.
  • Readings must be ± 0.4volt.
  • In case of an intermittent in DTC P0108, "Manifold Absolute Pressure Check" in this section should be consulted for better diagnosis.
  • The manifold absolute pressure (MAP) sensor signal voltage while moving related connectors and the wiring harness should be inspected if the connections seem to function correctly.
  •  The reading on the scan tool will automatically change if there is an induced failure.
  • This helps to separate the location of an intermittent malfunction.