Diagnostic Aids

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

Inspect for any vacuum leaks.
This DTC may set as the result of a misfire.
This DTC may set as the result of improper tension or alignment of the timing chain.
If this DTC is determined to be intermittent, refer to Intermittent Conditions .

DTC P0108

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check-Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Attempt to start the engine. Does the engine start and run?	-	Go to Step 3	Go to Step 4
3	Observe the MAP Sensor parameter with a scan tool. Is the voltage more than the specified value?	4.9 V	Go to Step 6	Go to Step 5
4	Turn OFF the ignition. Remove the manifold absolute pressure (MAP) sensor from the intake manifold. Refer to Manifold Absolute Pressure (MAP) Sensor Replacement . Leave the electrical harness connected. Connect a J 23738-A Mityvac to the MAP sensor. Apply vacuum until 5 inch Hg is reached. Observe the MAP Sensor parameter with the scan tool. Is the voltage more than the specified value?	4.9 V	Go to Step 6	Go to Diagnostic Aids
5	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition?	-	Go to Step 6	Go to Diagnostic Aids
6	Inspect for the following conditions: Disconnected, damaged, or incorrectly routed vacuum hoses The MAP sensor disconnected from the vacuum source Restrictions in the MAP sensor vacuum source Intake manifold vacuum leaks Did you find and correct the condition?	-	Go to Step 17	Go to Step 7
7	Turn OFF the ignition. Turn ON the ignition, with the engine OFF. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool. Is DTC P0641 also set?	-	Go to Step 10	Go to Step 8
8	Disconnect the MAP sensor electrical connector. Observe the MAP sensor parameter with the scan tool. Is the voltage less than the specified value?	0.1 V	Go to Step 9	Go to Step 11
9	Unless already done, remove the MAP sensor from the intake manifold. Refer to Manifold Absolute Pressure (MAP) Sensor Replacement . Connect a jumper wire between each of the terminals in the MAP sensor harness connector and the corresponding terminal at the MAP sensor. Refer to Using Connector Test Adapters in Wiring Systems. Measure the voltage from the low reference circuit of the MAP sensor at the jumper wire terminal to a good ground with the DMM. Refer to Measuring Voltage Drop in Wiring Systems. Is the voltage more than the specified value?	0.2 V	Go to Step 12	Go to Step 13
10	Disconnect the MAP sensor electrical connector. Observe the MAP sensor parameter with the scan tool. Is the voltage less than the specified value?	0.1 V	Go to DTC P0641	Go to Step 11
11	Test the MAP sensor signal circuit between the powertrain control module (PCM) and 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 17	Go to Step 16
12	Test the low reference circuit between the PCM and the MAP sensor for high resistance or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 14
13	Inspect for an intermittent and for a poor connection at the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 15
14	Inspect for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 17	Go to Step 16
15	Replace the MAP sensor. Refer to Manifold Absolute Pressure (MAP) Sensor Replacement . Did you complete the replacement?	-	Go to Step 17	-
16	Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement . Did you complete the replacement?	-	Go to Step 17	-
17	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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 18
18	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK