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.
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When does DTC set? |
Measures taken when DTC sets? |
When will DTC clear? |
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1) When the engine is idling. |
1) The Malfunction Indicator Lamp (MIL) will be seen glowing.
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1) The MIL will cease after four consecutive ignition cycles in which the diagnostic operates flawlessly.
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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.
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2) A history DTC will clear after 40 successive warm-up cycles without a fault |
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3) No throttle position sensor (TPS) fail conditions are present. |
3) A history DTC is stored. |
3) The scan tool will unset all DTCs |
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4) The MAP is > 95kPA |
4) The ECM replaces a fixed MAP. |
4) Disconnecting the ECM battery link for more than 10 seconds |
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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.