DTC P0108

Circuit Description

The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:

5-volt reference circuit
Low reference circuit
MAP sensor signal circuit

The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.

If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 will set.

Conditions for Running the DTC

DTCs P0606, P1120, P1125, P1220, P1221, P1271, P1272, P1273, P1275, P1276, P1280, P1281, P1285, P1286, P1514, P1515, P1516, and P1517 are not set.
The engine has been running for a length of time that is determined by the start-up coolant temperature. The length of time ranges from 2 minutes at less than -30°C (-22°F) to 1 second at more than 30°C (86°F).
The throttle angle is less than 0.5 percent when engine speed is less than 900 RPM.

Conditions for Setting the DTC

The MAP sensor signal voltage is more than 4.3 volts for 7 seconds.

Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

The MAP sensor 5-volt reference circuit is shared with other sensors. If DTC P1635 is set, this indicates that the 5-volt reference circuit is shorted to voltage and should be diagnosed first. The short may be on another sensor 5-volt reference circuit.
Operate the vehicle within the same conditions as when the DTC failed. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can aid in locating an intermittent condition.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics
1	Did you perform the Diagnostic System Check-Engine Controls?	--	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Install a scan tool. Start the engine. Monitor the DTC Information using the scan tool. Does the scan tool indicate that DTC P1635 is current?	--	Go to DTC P1635	Go to Step 3
3	Does the scan tool indicate that the manifold absolute pressure (MAP) sensor voltage is more than the specified value?	4.2 V	Go to Step 5	Go to Step 4
4	Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text or as close as possible to the Freeze Frame and/or Failure Records data that you observed. Does the DTC fail this ignition?	--	Go to Step 5	Go to Intermittent Conditions
5	Turn OFF the ignition. Inspect the MAP sensor vacuum source for the following conditions: Leaks Restrictions Faulty connections Did you find and correct the condition?	--	Go to Step 16	Go to Step 6
6	Disconnect the MAP sensor electrical connector. Turn the ignition ON, with engine OFF. Does the scan tool indicate that the MAP sensor voltage is less than the specified value?	0.1 V	Go to Step 7	Go to Step 9
7	Measure the voltage from the 5-volt reference circuit to the low reference circuit at the MAP sensor electrical connector. Does the voltage measure within the specified value range?	4.7-5.2 V	Go to Step 12	Go to Step 8
8	Does the voltage measure more than the specified value?	5.2 V	Go to Step 11	Go to Step 10
9	Test the signal circuit of the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 16	Go to Step 13
10	Test the low reference circuit of the MAP sensor for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 16	Go to Step 13
11	Important A short to voltage on the 5-volt reference circuit may also cause a MAP sensor failure. Test the 5-volt reference circuit of the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 16	Go to Step 13
12	Inspect for poor connections at the MAP sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 16	Go to Step 14
13	Inspect for poor connections at the PCM. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 16	Go to Step 15
14	Replace the MAP sensor. Refer to Manifold Absolute Pressure (MAP) Sensor Replacement . Did you complete the replacement?	--	Go to Step 16	--
15	Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?	--	Go to Step 16	--
16	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text. Does the DTC run and pass?	--	Go to Step 17	Go to Step 2
17	With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed?	--	Go to Diagnostic Trouble Code (DTC) List	System OK