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. 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).
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.■
  1. Check for continuity between heater control unit connector B (12P) No. 10 terminal and the in-car temperature sensor 2P connector No. 2 terminal.
Is there continuity?
YES -
Check for loose wires or poor connections at heater control unit connectors A (28P), B (12P), and at the in-car temperature sensor 2P connector. If the connections are good, substitute a known-good heater control unit, and recheck. If the symptom/indication goes away, replace the original heater control unit .■
NO -
Repair open in the wire between the heater control unit and the in-car temperature sensor.■