P2172-HIGH AIRFLOW/VACUUM LEAK DETECTED (INSTANTANEOUS ACCUMULATION)

For a complete wiring diagram Refer to Section 8W.

When Monitored:
Ignition on and engine running with no MAP Sensor DTCs.
Set Condition:
A large vacuum leak has been detected or both of the TP Sensors have failed based on their position being 2.5 volts and the calculated MAP value is less than the actual MAP minus an Offset value. One trip fault and the code will set within 5 seconds. ETC light will flash.

Possible Causes

VACUUM LEAK

RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT

(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT

(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND

RESISTANCE IN (K900) SENSOR GROUND CIRCUIT

RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

RESISTANCE IN THE TP SENSOR SIGNAL CIRCUIT

TP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

RESISTANCE IN THE (K922) TP SENSOR RETURN CIRCUIT

MAP SENSOR

TP SENSOR

PCM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).

Diagnostic Test

1.ACTIVE DTC

NOTE: The most likely cause of this DTC is a vacuum leak.

NOTE: Diagnose any 5-Volt Supply, TP Sensor, Fuel System Lean or Rich, or MAP Sensor DTCs before continuing.

NOTE: The throttle plate should be free from binding and carbon build up.

Is the DTC Active at this time?

Yes

Go To 2

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

2.VACUUM LEAK

NOTE: This code is enabled on engines with a plastic intake manifold and is intended to limit the maximum engine speed if a large crack occurs.

NOTE: A large vacuum leak is most likely the cause of this DTC.

Were any vacuum leaks found?

Yes

Repair the vacuum leak as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 3

3.MAP SENSOR OPERATION

Does the MAP Sensor voltage vary from below 2.0 volts at idle to above 3.5 volts at Wide Open Throttle?

Yes

Go To 4

Go To 13

4.TP SENSOR OPERATION

Is the voltage transition smooth between the appropriate values?

Yes

Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 5

5.RESISTANCE IN THE (F855) 5-VOLT SUPPLY CIRCUIT

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

Is the resistance above 100 ohms?

Yes

Go To 6

Repair the excessive resistance in the (F855) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

6.(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Is the resistance above 100 ohms?

Yes

Go To 7

Repair the short to ground in the (F855) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

7.TP SENSOR

Does the TP Sensor voltage change to the appropriate voltage with the jumper wire installed?

Yes

Disconnect the Battery before replacing the Throttle Body Assembly. Replace the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 8

8.RESISTANCE IN THE (K22) TP SENSOR NO.1 SIGNAL CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 9

Repair the excessive resistance in the (K22) TP Sensor No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

9.RESISTANCE IN THE (K122) TP SENSOR NO.2 SIGNAL CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 10

Repair the excessive resistance in the (K122) TP Sensor No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

10.(K22) TP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND

Is the resistance above 100 ohms for each circuit?

Yes

Go To 11

Repair the short to ground in the (K22) TP Sensor No.1 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

11.(K122) TP SENSOR NO.2 SIGNAL CIRCUIT SHORTED TO GROUND

Is the resistance above 100 ohms for each circuit?

Yes

Go To 12

Repair the short to ground in the (K122) TP Sensor No.2 Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

12.RESISTANCE IN THE (K922) SENSOR RETURN CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 19

Repair the excessive resistance in the (K922) TP Sensor Return circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

13.RESISTANCE IN THE (F856) 5-VOLT SUPPLY CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 14

Repair the excessive resistance in the (F856) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

14.(F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND

Is the resistance above 100k ohms?

Yes

Go To 15

Repair the short to ground in the (F856) 5-volt Supply circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

15.MAP SENSOR

Does the scan tool display MAP voltage from approximately 4.9 volts to below 0.5 volt with the jumper wire installed?

Yes

Replace the MAP Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Go To 16
NOTE: Remove the jumper wire before continuing.

16.RESISTANCE IN THE (K1) MAP SIGNAL CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 17

Repair the excessive resistance in the (K1) MAP Signal circuit
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

17.(K1) MAP SIGNAL CIRCUIT SHORTED TO GROUND

Is the resistance above 100k ohms?

Yes

Go To 18

Repair the short to ground in the (K1) MAP Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

18.RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT

Is the resistance below 5.0 ohms?

Yes

Go To 19

Repair the excessive resistance in the (K900) Sensor ground circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

19.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

Were there any problems found?

Yes

Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)