P0112

Code P0112, Intake Air Temperature (IAT) Sensor Circuit (Low Temp Indicated):

Intake Air Temperature (IAT), Engine Coolant Temperature (ECT), Throttle Position (TP), And Trans Temperature Sensors Wiring Schematic:

CIRCUIT DESCRIPTION
The Intake Air Temperature (IAT) sensor is a thermistor. The PCM applies 5 volts on CKT 472 to the sensor. When the air is cold, the sensor resistance is high, and the PCM will measure a high signal voltage. If the air is warm, the sensor resistance is low causing the PCM to measure a low voltage.


DTC PO112 WILL SET WHEN:
^ Engine coolant temperature above 60°C (140°F).
^ Mass air flow less than 12 grams per second.
^ Vehicle speed less than 25 mph.
^ IAT signal voltage indicates an intake air temperature below -34°C (-29°F) for 5 seconds.


ACTION TAKEN (PCM will default to):
With DTC P0112 set, the PCM will substitute a default value of 17°C (63°F) for intake air temperature DTC. P0112 will not illuminate the MIL (Service Engine Soon) lamp.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. A DTC P0112 will set due to an open sensor, wire, or connection. An open circuit would cause the Tech 1 to display approximately -40°C (-40°F). This test determines if the wiring and PCM are OK.

DIAGNOSTIC AIDS:
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Check for:
^ Poor connection or damaged harness - Inspect PCM harness connectors for backed out terminals "BF7" and/or, "WC6", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

^ Intermittent test - Observe IAT on Tech 1 while moving related connectors and wiring harness with warm engine running. If the failure is induced, the IAT display will change to a -4O° temperature reading. This may help to isolate the location of the malfunction.