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P0108



DTC P0107 or P0108

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Strategy Based Diagnosis
* Diagnostic Procedure Instructions

DTC Descriptors

DTC P0107
- Manifold Absolute Pressure (MAP) Sensor Circuit Low Voltage

DTC P0108
- Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage

Diagnostic Fault Information






Typical Scan Tool Data






Circuit/System Description

The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the MAP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The MAP sensor wiring includes 3 circuits. The control module supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The engine control module (ECM) supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the MAP sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation, the highest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehicle is operated at wide open throttle (WOT), or when the ignition is ON while the engine is OFF. Under these conditions, the ECM uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. The MAP can range from 11 kPa when pressures are low to as much as 103 kPa when pressures are high, depending on the BARO. The ECM monitors the MAP sensor signal for pressure outside of the normal range.

Conditions for Running the DTC

P0107
* DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0641, P0651 or P2135 are not set.
* The engine is running greater than or equal to 400 RPM.
* The throttle position is greater than or equal to 0 percent when the engine speed is less than or equal to 1,000 RPM.
OR
* The throttle position is greater than or equal to 12.5 percent when the engine speed is greater than 1,000 RPM.

P0108
* 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 5.5 minutes at less than -30°C (-22°F) to 10 seconds at more than +30°C (+86°F).
* DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 are not set.
* The engine is running.
* The throttle position is less than or equal to one percent when the engine speed is less than or equal to 1,200 RPM.
OR
* The throttle position is less than or equal to 20 percent when the engine speed is greater than 1,200 RPM.

Conditions for Setting the DTC

P0107
* The control module detects that the MAP sensor voltage is less than 0.05 volt for more than 5 seconds.
* This diagnostic runs continuously.

P0108
* The control module detects that the MAP sensor voltage is more than 4.9 volts for more than 5 seconds.
* This diagnostic runs continuously.

Action Taken When the DTC Sets

DTC P0107 and P0108 are Type B DTCs.

Conditions for Clearing the DTC

DTC P0107 and P0108 are Type B DTCs.

Circuit/System Verification

Important: Verify that the engine is in good mechanical condition before continuing with this diagnostic.

1. If DTCs P0641 or P0651 are set, refer Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
2. Verify the integrity of the entire air induction system by inspecting for the following conditions:

* Any damaged components
* Loose or improper installation
* An air flow restriction
* Any vacuum leak
* Improperly routed vacuum hoses
* In cold climates, inspect for any snow or ice buildup.

3. Verify that restrictions do not exist in the MAP sensor port or vacuum source.
4. Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust. Restricted Exhaust
5. The BARO that is used by the ECM to calculate the air flow models is initially based on the MAP sensor at ignition ON. When the engine is running, the ECM will continually update the BARO value near WOT using the MAP sensor and a calculation. A skewed MAP sensor will cause the BARO value to be inaccurate. Determine the current vehicle testing altitude. Ignition ON, observe the scan tool BARO Sensor parameter. Compare the parameter to the Altitude vs Barometric Pressure table. Refer to Altitude Versus Barometric Pressure.
6. A skewed MAP sensor will also cause the first and second intake manifold models to disagree with the actual MAP sensor measurements. Use the scan tool and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions.

Circuit/System Testing

Important: All electrical components and accessories must be turned OFF, and allowed to power down.

1. Ignition OFF, disconnect the harness connector at the MAP sensor.
2. Ignition OFF, test for less than 5 ohm of resistance between the low reference circuit terminal A and ground.

^ If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.

^ If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
^ If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool MAP parameter is less than 12 kPa.

^ If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal B and the 5-volt reference circuit terminal C. Verify the scan tool MAP parameter is greater than 103 kPa.

^ If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the MAP sensor.

Component Testing

1. Turn ON the ignition, with the engine OFF, and remove the MAP sensor.
2. Install a 3A fused jumper wire between the 5-volt reference circuit terminal C and the corresponding terminal of the MAP sensor.
3. Install a jumper wire between the low reference circuit terminal A of the MAP sensor and ground.
4. Install a jumper wire at terminal B of the MAP sensor.
5. Connect a DMM between the jumper wire from terminal B of the MAP sensor and ground.
6. Install the J 23738-A to the MAP sensor vacuum port. Slowly apply vacuum to the sensor while observing the voltage on the DMM. The voltage should vary between 0-5.2 volts, without any spikes or dropouts.

^ If the voltage is not within the specified range or is erratic, replace the MAP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Manifold Absolute Pressure Sensor Replacement
* Refer to Programming and Relearning. Programming and Relearning
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