Diagnostic Procedure

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DTC B1B71, B1B71 DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	INSPECT EVAPORATOR TEMPERATURE SENSOR Inspect the evaporator temperature sensor See EVAPORATOR TEMPERATURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER] . Is it normal?	Yes	Go to the next step.
1		No	Replace the evaporator temperature sensor. See A/C UNIT DISASSEMBLY/ASSEMBLY .
2	INSPECT EVAPORATOR TEMPERATURE SENSOR CIRCUIT FOR OPEN CIRCUIT Disconnect the climate control unit connector and the evaporator temperature sensor connector Is there an open circuit in the wiring harness between the following terminals of the climate control unit and the evaporator temperature sensor? 2E-A 2L-C	Yes	Repair the wiring harness.
2		No	Go to the next step.
3	INSPECT EVAPORATOR TEMPERATURE SENSOR CIRCUIT FOR SHORT TO GROUND Is there a short circuit to ground in the wiring harness between climate control unit terminal 2E and evaporator temperature sensor terminal A?	Yes	Repair the wiring harness.
3		No	Connect the climate control unit connector, then go to the next step.
4	INSPECT EVAPORATOR TEMPERATURE SENSOR CIRCUIT Switch the ignition to ON Inspect the voltage at the following climate control unit terminal (wiring harness-side) Terminal 2E (evaporator temperature sensor input signal) Is the voltage normal? (Approx. 5 V)	Yes	The system is normal at present. (Clear the past malfunction from the memory.
4		No	Inspect the connection of the climate control unit connector.