DTC P24D7: EVAP System Pressure Sensor/Switch "B" Circuit Low: Notes

DTC detecting condition: 

Immediately at fault recognition

Wiring diagram: 

Engine Electrical System Ref. to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC P06B4 displayed? (Current code)

   Yes:  Check for DTC P06B4. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P06B4 SENSOR POWER SUPPLY "B" CIRCUIT LOW .

   No:  Go to  2.

2. CHECK DTC  .

   Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC P06B5 displayed? (Current code)

   Yes:  Check for DTC P06B5. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P06B5 SENSOR POWER SUPPLY "B" CIRCUIT HIGH .

   No:  Go to  3.

3. CHECK DATA MONITOR  .
   1. Start the engine.
   2. Using the Subaru Select Monitor, read the value in [Purge Line Pressure].
   NOTE: For detailed operation procedures, refer to "COMMON (DIAGNOSTICS)". Ref. to COMMON (DIAGNOSTICS)>DATA MONITOR .

   Is the value of [Purge Line Pressure] less than 38.63 [kPa] (290 mmHg, 11.4 inHg)?

   Yes:  Go to  4.

   No:  Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
4. CHECK CPC PRESSURE SENSOR POWER SUPPLY  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from CPC pressure sensor.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between CPC pressure sensor connector and engine ground.

      Connector & terminal 

      (E80) No. 3 (+) - Engine ground (-):

   Is the voltage 4.5 V or more?

   Yes:  Go to  5.

   No:  Repair the following item.

   • Open circuit in harness between ECM connector and CPC pressure sensor connector
   • Poor contact of ECM connector
   • Poor contact of J/C
5. CHECK HARNESS BETWEEN ECM AND CPC PRESSURE SENSOR CONNECTOR (OPEN)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Measure the resistance of harness between ECM connector and CPC pressure sensor connector.

      Connector & terminal 

      (E51) No. 50 - (E80) No. 2:

   Is the resistance less than 1 Ω?

   Yes:  Go to  6.

   No:  Repair the open circuit in harness between ECM connector and CPC pressure sensor connector.

6. CHECK HARNESS BETWEEN ECM AND CPC PRESSURE SENSOR CONNECTOR (SHORT TO GROUND)  .

   Measure the resistance between CPC pressure sensor connector and engine ground.

   Connector & terminal 

   (E80) No. 2 - Engine ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  7.

   No:  Repair the ground short circuit of harness between ECM connector and CPC pressure sensor connector.

7. CHECK FOR POOR CONTACT  .

   Check for poor contact of ECM and CPC pressure sensor connector.

   Is there poor contact of the ECM or CPC pressure sensor connector?

   Yes:  Repair the poor contact of the ECM or CPC pressure sensor connector.

   No:  Replace the CPC pressure sensor. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DOTC)>CPC PRESSURE SENSOR .