Code No. P0112: Intake Air Temperature Sensor Circuit Low Input

OPERATION

• A power voltage of 5 V is applied to the intake air temperature sensor power terminal of air flow sensor from the engine-ECU connector terminal ATS.
  
• The power voltage is earthed to the engine-ECU connector terminal AFSE from the intake air temperature sensor connector terminal.
  

FUNCTION

• The intake air temperature sensor converts the intake air temperature into a voltage and inputs the voltage signal to the engine-ECU.
  
• In response to the signal, the engine-ECU corrects the fuel injection amount, etc.
  
• The intake air temperature sensor is a kind of resistor, which has characteristics to reduce its resistance as the intake air temperature rises. Therefore, the sensor output voltage varies with the intake air temperature, and becomes lower as the intake air temperature rises.
  

TROUBLE JUDGMENT

• More than 2 seconds have passed since the engine starting sequence was completed.
  

• Intake air temperature sensor output voltage is less than 0.2 V (corresponding to an intake air temperature of 115°C or more) for 2 seconds.
  

FAIL-SAFE AND BACKUP FUNCTION

• Control as if the intake air temperature is 25°C.
  

PROBABLE CAUSES

• Failed intake air temperature sensor
  
• Short circuit in intake air temperature sensor circuit or loose connector contact
  
• Failed engine-ECU
  

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Go to Step 2.

	Go to Step 3.

	Repair or replace the connector, or replace the air flow sensor.

	Go to Step 5.

	Go to Step 4.

	Go to Step 5.

	Repair or replace the connector, or repair the damaged harness wire.

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU.