B1412 LEXUS, SCION, TOYOTA: AMBIENT TEMPERATURE SENSOR CIRCUIT
POST UPDATED IN June, 2023
B1412 Code failures by brands
Description of DTC code B1412
The Ambient Temperature Sensor is located ahead of the condenser and is used to sense the ambient temperature to control the air conditioning. This sensor is attached to the combination meter and detects all temperature changes, and the information it provides is employed for room temperature control.
A signal is sent from the room temperature sensor to the air conditioner amplifier via the combination meter. The resistance of this sensor varies according to the temperature. When the resistance increases, it is due to a low temperature, and if the temperature increases, the resistance consequently decreases. The air conditioner amplifier sends a 5-volt reference to the Ambient Temperature Sensor and reads the voltage changes which it interprets as changes in resistance. The combination meter provides a reading signal to the A/C amplifier via CAN communication.
When the B1412 OBDII diagnostic code is set it means that a malfunction was found in the Ambient Temperature Sensor.
Symptoms of fault code B1412
- Check Engine Lamp illuminated.
Causes of OBD2 B1412
B1412 OBD2 fault code is set for the following reasons:
- Ambient Temperature Sensor wires may have been damaged.
- The Ambient Temperature Sensor circuit could be shorted due to poor connections.
- The Ambient Temperature Sensor may be defective.
- The combination meter may be faulty.
- The A/C amplifier may have been damaged.
Possible solutions of the DTC code B1412
In order to resolve the DTC B1412 OBDII code you must do the following:
- Consult the Technical Service Bulletins as a first step.
- Inspect the Ambient Temperature Sensor circuit wiring and connections. If any of these components are damaged due to corrosion or wear, make the appropriate repairs.
- Check the Ambient Temperature Sensor circuit for poor connections that could cause an open or short circuit. If the circuit voltages are inconsistent, make adjustments.
- Measure the resistance of the ambient temperature sensor and compare it to the value indicated on the vehicle's data source. If an out-of-range resistance is found, replace the sensor.
