DTC B1430: In-Vehicle (Post Evaporator) Temperature Sensor Circuit Open

DTC detecting condition: 

In-vehicle sensor circuit is open.

Trouble symptom: 

In-vehicle air temperature is falsely recognized as 25°C (77°F), and the compartment temperature is adjusted.

• Without humidity sensor

Wiring diagram: 

Air conditioning system Ref. to WIRING SYSTEM (IMPREZA MODEL)>AIR CONDITIONING SYSTEM>WIRING DIAGRAM . Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

• With humidity sensor

Wiring diagram: 

Air conditioning system Ref. to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR  .
   1. Check connecting condition of the A/C control panel connector, in-vehicle sensor connector (without humidity sensor) or temperature and humidity sensor connector (with humidity sensor).
   2. Turn the ignition switch to ON.
   3. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1430 displayed? (Current malfunction)

   Yes:  Go to  2.

   No:  Even if DTC is displayed, 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.
2. CHECK IN-VEHICLE SENSOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the in-vehicle sensor (without humidity sensor) or temperature and humidity sensor (with humidity sensor). Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>IN-VEHICLE SENSOR (AUTO A/C MODEL) .
   3. Short the connector (i173) (without humidity sensor) or the connector (i55) (with humidity sensor).
   4. Turn the ignition switch to ON.
   5. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1431 displayed? (Current malfunction)

   Yes: 

   • Without humidity sensor

   Replace the in-vehicle sensor. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>IN-VEHICLE SENSOR (AUTO A/C MODEL) .

   • With humidity sensor

   Replace the temperature and humidity sensor. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>TEMPERATURE AND HUMIDITY SENSOR .

   No:  Go to  3.

3. CHECK HARNESS  .
   1. Turn the ignition switch to OFF.
   2. Restore the temporary shorted lines made in step 2.
   3. Turn the ignition switch to ON.
   4. Using a tester, measure the voltage between terminals in in-vehicle sensor connector (without humidity sensor) or temperature and humidity sensor connector (with humidity sensor).

      Connector and terminal 

      Without humidity sensor

      (i173) No. 1 (+) - (i173) No. 2 (-):

      With humidity sensor

      (i55) No. 1 (+) - (i55) No. 2 (-):

      Is the voltage 4.5 - 5.5 V?

      Yes:  Go to  4.

      No:  Repair or replace the open circuit of harness.

4. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the A/C control panel.
   3. Using a tester, check the continuity between the A/C control panel connector and in-vehicle sensor connector (without humidity sensor) or temperature and humidity sensor connector (with humidity sensor).

      Connector and terminal 

      Without humidity sensor

      (i173) No. 1 - (i88) No. 12:

      (i173) No. 2 - (i88) No. 30:

      With humidity sensor

      (i55) No. 1 - (i88) No. 12:

      (i55) No. 2 - (i88) No. 30:

      Is there continuity?

      Yes:  Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)>CONTROL PANEL .

      No:  Repair or replace the open circuit of harness.