DTC B1434: Evaporator Temperature Sensor Circuit Open

DTC detecting condition:

Open circuit in the evaporator sensor is detected for 3 seconds or more.

Trouble symptom:

Evaporator temperature is falsely recognized as low, and the compartment temperature is adjusted.

Wiring diagram:

Air conditioning system Refer to WIRING SYSTEM>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK CONNECTOR.
1. Check the condition of connector connection.
2. Read the DTC using Subaru Select Monitor. Refer to HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC B1434 displayed?

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.
CHECK EVAPORATOR SENSOR.
1. Disconnect the evaporator sensor.
2. Short the evaporator sensor connector (B88).
3. Read the DTC using Subaru Select Monitor. Refer to HVAC SYSTEM (AUTO A/C) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC B1435 displayed?

Yes Replace the evaporator sensor. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>EVAPORATOR>REMOVAL .

No: Go to 3.
CHECK HARNESS.
1. Restore the temporary shorted lines made in step 2.
2. Turn the ignition switch to ON.
3. Using the tester, measure the voltage between terminals.
Connector & terminal

(B88) No. 2 (+) - No. 1 (-):

Is the voltage 4.5 - 5.0 V?

Yes: Go to 4.

No Repair or replace the open circuit of harness.
CHECK HARNESS (OPEN CIRCUIT).
1. Disconnect the connector from the A/C control panel.
2. Using a tester, check continuity between terminals.
Connector & terminal

(B88) No. 1 - (i88) No. 14:

(B88) No. 2 - (i88) No. 18:

Is there continuity?

Yes Replace the A/C control panel. Refer to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>CONTROL PANEL>REMOVAL .

No Repair or replace the open circuit of harness.