DTC Troubleshooting: B1225 (A and AUTO)
DTC B1225 or DTC indicator A and AUTO:
 An Open in the In-car Temperature Sensor Circuit
  1. Clear the DTC with the HDS.
  1. Turn the ignition switch to LOCK (0) and then to ON (II).
  1. Do the self-diagnostic with the HDS or the heater control unit.
  1. Check for DTCs.
Is DTC B1225 or A and AUTO indicated?
YES -
Go to Step 5 .
NO -
Intermittent failure; check for loose wires or poor connections on the in-car temperature sensor circuit.■
  1. Turn the ignition switch to LOCK (0).
  1. Remove the in-car temperature sensor, and test it.
Is the in-car temperature sensor OK?
YES -
Go to Step 7 .
NO -
Replace the in-car temperature sensor .■
  1. Disconnect heater control unit connectors A (28P) and B (12P).
  1. Check for continuity between heater control unit connector A (28P) No. 26 terminal and the in-car temperature sensor 2P connector No. 1 terminal.
Is there continuity?
YES -
Go to Step 9 .
NO -
Repair open in the wire between the heater control unit and the in-car temperature sensor.■