Circuit Description

Fig 1: Intake Air Temperature Sensor Resistance Graph

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The intake air temperature (IAT) sensor is built into the mass air flow (MAF) meter, and monitors the intake air temperature. The IAT sensor has a built-in thermistor with a resistance that varies according to the IAT. When the IAT is low, the resistance in the thermistor increases.

When the IAT is high, the resistance decreases. These variations in resistance are transmitted to the ECM terminal as voltage changes. (See illustration)

5 V are applied to the IAT sensor from terminal THA of the ECM via resistor R, which is connected to the IAT sensor in series. When the resistance of the IAT changes, in accordance with changes in IAT, the voltage at terminal THA also changes. Based on this signal, the ECM increases the furl injection volume to improve the driveability of the vehicle during cold engine operation.

Fig 2: DTC Chart

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HINT:

When DTC P0110 is detected, check the intake air temperature by selecting the following menu items on the hand-held tester or the OBD II scan tool: DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / INTAKE AIR.