Code P0112, IAT Sensor Circuit (Low Temperature Indicated): Notes

WARNING: This page is about a different car, the 1994 Oldsmobile Ninety-Eight and 1994 Buick Park Avenue. However, it is still accessible from the selected car via links, so may be relevant.

The Intake Air Temperature (IAT) sensor is a thermistor. PCM applies and monitors 5 volts to sensor. When air is cold, sensor resistance is high and PCM will measure a high signal voltage. If air is warm, sensor resistance is low causing PCM to measure low voltage. Code P0112 will set when the following conditions are present.

Engine coolant temperature is greater than 140°F (60°C).
Mass air flow is less than 12 grams per second.
Vehicle speed is less than 25 MPH.
IAT signal voltage indicates an intake air temperature less than -29°F (-34°C) for 5 seconds.

With Code P0112 set, PCM will substitute a default value of 61°F (16°C) for intake air temperature. Code P0112 does not illuminate the Malfunction Indicator Light (MIL).

NOTE: Test numbers refer to numbers on diagnostic chart.

An open sensor, wire or connection will cause Code P0112 to set. An open circuit would cause Tech-1 to display approximately -40°F (-40°C). This test determines if wiring and PCM are okay.