P2172 High Airflow/Vacuum Leak Detected (Instantaneous Accumulation)

P2172 code - When monitored this DTC the engine running at or above idle (not cranking), no MAP sensor DTCs, no throttle body related DTCs, no 5-volt reference DTCs, no crank/cam sensor DTCs, DTC P2174 is not present. Set condition the PCM detects an increase in the difference between the actual Map pressure sense and calculated map sensor value, beyond a calibrated limit, due to a loss of vacuum.

P2172 code
Default actions:
- The ETC light flash
- The MIL light illuminate

Possible causes P2172 code

- Vacuum leak
- Restriction in the exhaust system
- Internal engine mechanical components
- Resistance in the 5-volt supply circuit
- Resistance in the MAP signal circuit
- Resistance in MAP sensor ground circuit
- Map sensor
- Powertrain Control Module (PCM)

Diagnostic test P2172 code

Step 1. Check for an active DTC
Diagnose any 5-volt supply, TPS, Cam Sensor, Crank Sensor or MAP sensor DTCs before continuing. Stert the engine and allo it to idle until closed loop fueling is archived. With the scan tool, read DTCs.

Is the DTC active or pending?

Yes, go to step 2.
No, perform the PCM intermittent condition.

Step 2. Compare the engine vacuum and MAP sensor reading
Turn the ignition off connect a vacuum gauge to the intake manifold. Start the engine anf allow it to idle, monitor the reading on the vacuum gauge. Monitor the MAP sensor reading on the scan tool. The minimum engine vacuum at idle should be no less than approximately 13.0 HG.

Compare the scan tool reading to the vacuum gauge reading?

Both of the readings match and are below 13.0 HG, check and repair any engine vacuum leaks, exhaust restrictions, or engine mechanical conditions that can cause low engine compression.

Engine vacuum is normal and MAP reading on scan tool does not match, go to step 3.

Step 3. Check for high resistance in the 5-volt supply circuit
Turn the ignition off, disconnect the MAP sensor harness connector. Disconnect the PCM harness connector. Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Measure the resistance of the 5-Volt supply circuit between the MAP sensor harness connector and PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes, go to step 4.
No, repair the 5-volt supply circuit for high resistance.

Step 4. Check for high resistance in the MAP signal circuit
Measure the resistance of the MAP signal circuit between the MAP sensor harness connector and PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes, go to step 5.
No, repair the MAP signal circuit for high resistance.

Step 5. Check for high resistance in the sensor ground circuit
Measure the resistance of the sensor ground circuit between the MAP sensor harness connector and the PCM harness connector.

Is the resistance below 5.0 Ohms?

Yes, go to step 6.
No, repair the excessive sensor ground circuit for high resistance.

Step 6. Check the MAP sensor and port for obstructions
Remove the MAP sensor, inspect the MAP sensor and port for any obstructions.

Were any obstructions found?

Yes, perform the appropriate repairs and retest.
No, go to step 7.

Step 7. MAP sensor
Replace the MAP sensor, turn the ignition on. With the scan tool erase DTCs, start the engine and allow it to idle until closed loop fueling is archived. With the scan tool read DTCs.

Did the DTC return?

Yes, go to step 8.
No, repair is complete.

Step 8. Check related PCM and component connections

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