DTC P0112: Intake Air Temperature Circuit Low Input; DTC P0113: Intake Air Temperature Circuit High Input [08/2015 - ]: Description

Fig 1: Variations In Resistance Are Transmitted To ECM As Voltage Changes

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1. The intake air temperature sensor, mounted on the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).
2. The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
3. Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.

   HINT: 

   When DTC P0112 or P0113 is stored, the ECM enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the ECM. The ECM continues operating in fail-safe mode until a pass condition is detected.

HINT: 

When either of these DTCs is stored, check the intake air temperature by entering the following menus: Powertrain / Engine and ECT / Data List / Intake Air.