Circuit description

Inlet temperature sensor, which is built into the intake air flow meter sub-assembly, detects intake air temperature. The resistance of the thermistor built into the inlet air temperature sensor changes as the intake air temperature varies. The lower the intake air temperature, the greater the thermistor resistance, and the higher the intake air temperature, the lower the thermistor resistance. The inlet air temperature sensor is connected to the engine control computer. The 5-V power supply voltage is supplied from THA terminal of the computer, and grounded in the computer via the resistor integrated into the inlet air temperature sensor. Therefore, since the resistor and the inlet air temperature sensor are connected in series, the resistance changes as the inlet air temperature changes, and the potential at the THA terminal also changes. Based on this signal, the engine control computer increases the fuel injection amount to improve driveability when the engine is cold.

NOTE: When either of these DTCs is stored, the engine control computer enters fail-safe mode. The engine control computer fixes the inlet air temperature at 20°C {68°F} during the fail-safe mode operation. The engine control computer continues fail-safe mode operation until the normal condition is restored.

DTC DETECTION CONDITION

DTC No.	DTC detection condition	Suspected parts
P0111	Difference between maximum and minimum values in inlet air temperature sensor voltage is less than 0.02 V. (2 trips detection logic)	Inlet air temperature sensor (integrated into intake air flow meter sub-assembly)