Circuit Description

Intake Air Temperature (IAT) sensor uses a thermistor (a variable resistor) in series with a fixed resistor inside PCM to control signal voltage to PCM. IAT sensor is located in air cleaner housing. PCM applies 5 volts to IAT sensor. PCM monitors voltage across IAT sensor and converts it into a temperature reading. When outside air temperature is cold, IAT sensor resistance is high. When outside air temperature is warm, IAT sensor resistance is low. DTC will set when engine is running and IAT sensor signal voltage indicates a smaller change than expected in voltage input during a warm-up cycle.

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault. PCM will record operating conditions at time of diagnostic failure and store information in FREEZE FRAME/FAILURE RECORDS data buffer.