GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2007 🢒 VUE - AWD 🢒 DTC 🢒 DTC P2172

Diagnostic Instructions
    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each of the diagnostic category.

DTC Descriptors

DTC P2172: Sudden High Airflow Detected

Circuit/System Description

The engine control module (ECM), based on information from various sensors, determines the desired engine speed. The ECM monitors the crankshaft position (CKP) sensor and the transmission output shaft speed sensor to determine when an engine idle condition is present. When the engine is idling a desired engine speed is determined by the ECM. When the actual engine speed exceeds the desired engine speed, a DTC is set along with a reduced engine power mode.

Conditions for Running the DTC
    • DTCs P0068, P0107, P0108, P0112, P0113, P0117, P0118, P0120, P0122, P0123, P0125, P0171, P0172, P0201, P0202, P0203, P0204, P0220, P0300, P0336, P0442, P0446, P0452, P0453, P0641, P0651, P1516, P2101, P2135, P2176 are not set.
    • The engine is operating for at least 3 seconds.
    • The engine coolant temperature (ECT) is more than -40°C (-40°F).
    • The intake air temperature (IAT) is more than -40°C (-40°F).
    • The barometric pressure (BARO) is more than 0kPa.
    • The system voltage is between 9-18 volts.
    • The vehicle speed is less than 5 km/h (3 mph).
    • Idle speed conditions are met for at least 6 seconds.
    • DTC P2172 runs continuously when the above conditions are met.

Conditions for Setting the DTC
    • The actual idle speed is approximately 500 RPM greater than the desired idle speed.
    •  The above condition is present for 0.5 second.

Action Taken When the DTC Sets

DTC P2172 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P2172 is a Type A DTC.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Controls Connector End Views
    •  Engine Control Module Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification
  1. If there are any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  2. Compare the desired engine idle speed to the actual engine idle speed with a scan tool. Actual engine idle speed should be no greater than or less than 100 RPM of desired.
  3. With a scan tool in output controls, increase the engine speed in 25 RPM increments while comparing the desired engine speed to the actual engine speed. The actual engine speed should stay within 25 RPM of the desired engine speed.

Circuit/System Testing
  1. Ensure proper operation of the CKP sensor. Refer to DTC P0335 or P0336.
  2. Ensure proper operation of the transmission output speed sensor (OSS). Refer to DTC P0722 for the 4T45-E transmission.
  3. Inspect for any condition that can increase idle speed.
    4. • Vacuum leaks
    • Un-metered air entering the engine, after the mass airflow
    • A faulty positive crankcase ventilation (PCV) valve

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.