P0112

DTC P0112:

CIRCUIT DESCRIPTION
The Intake Air Temperature (IAT) sensor is a thermistor. The Powertrain Control Module (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.

DIAGNOSTIC TROUBLE CODE (DTC) P0112 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 16°C (61°F) for intake air temperature. DTC P0112 does not illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC CHART 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 "BB7" and/or, "BA8", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test
Observe Intake Air Temperature (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 400 temperature reading. This may help to isolate the location of the malfunction.