Beretta V6-3100 3.1L VIN M SFI (1995)
Intake Air Temperature Sensor: Description and Operation
PURPOSE
The Intake Air Temperature (IAT) sensor is used to control spark timing and delays Exhaust Gas Regulator (EGR) when the intake air is cold.
OPERATION
The IAT sensor is a thermistor (a resistor which changes value based on the temperature of air entering the engine and is mounted in the air
cleaner). Low temperature produces a high resistance approximately 100,000 ohms at 4O°C (-40°F) while high temperature causes low resistance
approximately 70 ohms at 130°C (266°F). The Powertrain Control Module (PCM) supplies a 5 volts signal to the sensor through a resistor in the
PCM and measures the voltage. The voltage will he high when the intake air is cold and low when the air is hot. By measuring the voltage the
PCM calculates the intake air temperature.
A failure in the IAT sensor circuit should set either a Diagnostic Trouble Code (DTC) 23 or DTC 25. Once a diagnostic trouble code is set, the
PCM will use an artificial default value for IAT and some vehicle performance will return.
