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Home >> Honda >> 2012 >> Odyssey EX-L >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Climate Control >> DTC Troubleshooting >> DTC B1231 or DTC indicator G and AUTO: An Open in the Evaporator Temperature Sensor Circuit (Front)

DTC B1231 or DTC indicator G and AUTO: An Open in the Evaporator Temperature Sensor Circuit (Front)

  1. Clear the DTCs with the HDS.
  2. Turn the ignition switch to LOCK (0), and then back to ON (II).
  3. Do the Self-Diagnostic Function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS  ) or the climate control unit (see HOW TO USE THE CLIMATE CONTROL UNIT SELF-DIAGNOSTIC FUNCTION WITHOUT THE HDS  ).
  4. Check for DTCs.

    Is DTC B1231 or G and AUTO indicated? 

    YES  -Go to step 5.

    NO  -Intermittent failure. Check for loose wires or poor connections on the front evaporator temperature, sensor circuit.

  5. Turn the ignition switch to LOCK (0).
  6. Remove the front evaporator temperature sensor (see INSTALLATION ), and test it (see EVAPORATOR TEMPERATURE SENSOR TEST ).

    Is the front evaporator temperature sensor OK? 

    YES  -With the front evaporator temperature sensor disconnected, go to step 7.

    NO  -Replace the front evaporator temperature sensor (see INSTALLATION ).

  7. Disconnect climate control unit connector A (28P).
  8. Check for continuity between climate control unit connector A (28P) terminal No. 22 and front evaporator temperature sensor 2P connector terminal No. 2.
    Fig 1: Checking Continuity Between Climate Control Unit And Front Evaporator Temperature Sensor Connector Terminal
    G06968304Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Go to step 9.

    NO  -Repair an open in the wire between the climate control unit and the front evaporator temperature sensor.

  9. Check for continuity between climate control unit connector A (28P) terminal No. 13 and front evaporator temperature sensor 2P connector terminal No. 1.
    Fig 2: Checking Continuity Between Climate Control Unit And Front Evaporator Temperature Sensor Connector Terminal
    G06968305Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  -Check for loose wires or poor connections at climate control unit connector A (28P) and at the front evaporator temperature sensor 2P connector, If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION  ).

    NO  -Repair an open in the wire between the climate control unit and the front evaporator temperature sensor.