Troubleshooting

DTC P0110 - Intake Air Temperature Circuit Malfunction





CIRCUIT DESCRIPTION
The intake air temp. sensor is built into the air flow meter and sensors the intake air temp.
A thermistor built in the sensor changes the resistance value according to the intake air temp.,The lower the intake air temp.,the greater the thermistor resistance value, and the higher the intake air temp., the lower the thermistor resistance value (See fig.1).
The air intake temp. sensor is connected to the ECM (See below). The 5V power source voltage in the ECM is applied to the intake temp. sensor from the terminal THA via a resistor R.
That is, the resistor R and the intake air temp. sensor are connected in series. When the resistance value of the intake air temp. sensor changes in accordance with changes in the intake air temp., the potential at terminal THA also changes. Based on this signal, the ECM increases the fuel injection volume to improve driveability during cold engine operation.
If the ECM detects the DTC "P0110", it operates the fail safe function in which the intake air temp. is assumed to be 20°C (68°F).





DETECTING CONDITION





HINT: After confirming DTC "P0110" use the OBD II scan tool or TOYOTA hand-held tester to confirm the intake air temp. from "CURRENT DATA".





WIRING DIAGRAM

















INSPECTION PROCEDURE

HINT: If DTC P0110 (Intake Air Temp. Circuit Malfunction), P0115 (Engine Coolant Temp. Circuit Malfunction), P0120 (Throttle/Pedal Position Sensor/Switch "A" Circuit Malfunction) are output simultaneously, E2 (Sensor Ground) may be open.