Code No.B103A: Refrigerant pressure sensor system (short to power supply)
Code No.B103B: Refrigerant pressure sensor system (open or short to earth)


This diagnosis code will be stored when the refrigerant pressure sensor circuit is short to power supply (Code No.B103A) or open or short to earth (Code No.B103B).


  • Malfunction of the A/C pressure sensor
  • Damaged wiring harness or connectors
  • Malfunction of the heater controller assembly (A/C-ECU)


STEP 1. M.U.T.-III data list

Check that the following service data display contents are normal. (Refer to ).
Item No.109: Refrigerant pressure sensor

Q. Is the check result normal?

Go to Step 4.
Go to Step 2.

STEP 2. Check of open and short circuit in SENB, AC/P, SENG - line between A/C pressure sensor and auto heater controller assembly (A/C-ECU) connector.

Q. Is the check result normal?

Go to Step 3.
Repair the connector(s) or wiring harness.

STEP 3. Check the A/C pressure sensor.

Refer to.

Q. Is the check result normal?

Go to Step 4.
Replace the A/C pressure sensor.

STEP 4. Check whether the diagnosis code is stored again.

Q. Is the diagnosis code stored?

Replace the heater controller assembly (A/C-ECU).
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).