Subaru Crosstrek Service Manual: Dtc b1431 in-vehicle (post evaporator) temperature sensor circuit short-circuit

DTC detecting condition:

In-vehicle sensor circuit is shorted.

Trouble symptom:

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

Wiring diagram:

Air conditioning system Air Conditioning System > WIRING DIAGRAM">

1.CHECK CONNECTOR.

1) Check the condition of connector connection.

2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is B1431 displayed?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT">Go to Step 2.

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) Disconnect the in-vehicle sensor. In-Vehicle Sensor (Auto A/C Model) > REMOVAL">

2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)">

Is B1430 displayed?

Replace the in-vehicle sensor. In-Vehicle Sensor (Auto A/C Model) > REMOVAL">

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT">Go to Step 3.

3.CHECK HARNESS.

1) Turn the ignition switch to ON.

2) Using the tester, measure the voltage between terminals.

Connector & terminal

(i55) No. 2 (+) — No. 1 (−):

Is the voltage 4.5 — 5.0 V?

Check the connection of the in-vehicle sensor circuit.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1431 IN-VEHICLE (POST EVAPORATOR) TEMPERATURE SENSOR CIRCUIT SHORT-CIRCUIT">Go to Step 4.

4.CHECK HARNESS (SHORTED BETWEEN LINES).

1) Disconnect the connector from the A/C control panel.

2) Using a tester, check continuity between terminals.

Connector & terminal

(i55) No. 1 — No. 2:

Is there continuity?

Repair or replace the short circuit of the harness.

Replace the A/C control panel. Control Panel > REMOVAL">

Dtc b1430 in-vehicle (post evaporator) temperature sensor circuit open

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