P0108

Steps 1 - 3:

Steps 4 - 7:

Steps 8 - 11:

Step 12:

DTC P0108 Manifold Absolute Pressure (MAP) Circuit High Input




Circuit Description
The manifold absolute pressure (MAP) sensor responds to changes in intake manifold pressure. The MAP sensor signal voltage to the powertrain control module (PCM) varies from below 2 volts at idle (low manifold pressure) to above 4 volts with the ignition ON, engine not running or at wide-open throttle (high manifold pressure).

A "speed density" method of determining engine load is used on this engine. This is calculated using inputs from the MAP sensor, RPM, CKP Sensor, and the Intake Air Temperature (IAT) sensor. The MAP sensor is the main sensor used in this calculation, and measuring engine load is its main function. The MAP sensor is also used to determine manifold pressure changes while the exhaust gas recirculation (EGR) flow test diagnostic is being run, to determine engine vacuum level for some other diagnostics and to determine barometric pressure (BARO). Refer to DTC P0401.

The PCM monitors the MAP signals for voltages outside the normal range (10 - 104 kPa) of the MAP sensor. If the PCM detects a MAP signal voltage that is excessively low, Diagnostic Trouble Code P0108 will be set. DTC P0108 is a Type A Code.

Conditions for Setting the DTC
- No TP sensor Diagnostic Trouble Codes present.
- Engine is running.
- Throttle position is below 2.7 % if engine speed is below 1000 RPM.
- Throttle position is below 10 % if engine speed is above 1000 RPM.
- The MAP sensor indicates manifold absolute pressure above 90 kPa for a total of approximately 10 seconds over a 16-seconds period.

Action Taken When the DTC Sets
- The PCM will illuminate the malfunction indicator lamp (MIL) after the second consecutive trip in which the fault is detected.
- The PCM will default to a BARO value of 79.3 kPa.
- The PCM will store conditions which were present when the Diagnostic Trouble Code was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The PCM will turn the MIL OFF on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- A history Diagnostic Trouble Code P0108 will clear after 40 consecutive warm-up cycles have occurred without a fault.
- Diagnostic Trouble Code P0108 can be cleared by using the Scan Tool's "Clear Info" function.

Diagnostic Aids
Check for the following conditions:
- Poor connection at PCM - Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
- The MAP sensor shares a 5 Volt Reference with the TP sensor and Fuel Pressure sensor.

If these codes are also set, it could indicate a problem with the 5 Volt reference circuit.

- The MAP sensor share a ground with the TP sensor and Fuel Pressure sensor.
- Damaged harness - Inspect the wiring harness for damage; an open circuit, a short to ground, or a short to voltage. If the harness appears to be OK, observe the MAP display on the Tech 2 while moving connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault.

If Diagnostic Trouble Code P0108 cannot be duplicated, the information included in the Failure Records data can be useful in determining vehicle mileage since the Diagnostic Trouble Code was last set.