2001 Chevrolet/Geo Camaro  

DTC P0112

Circuit Description

The intake air temperature (IAT) sensor is a thermistor which measures the temperature of the air entering the engine. The powertrain control module (PCM) applies 5 volts through a pull up resistor. When the intake air is cold, the sensor resistance is high and the PCM will monitor a high signal voltage on the IAT sensor signal circuit. As the intake air warm, the sensor resistance becomes lower causing the PCM to monitor a lower voltage. If the PCM detects an excessively low IAT sensor signal voltage, which indicates a high temperature, DTC P0112 will set.

Conditions for Running the DTC
Conditions for Setting the DTC
Action Taken When the DTC Sets
Conditions for Clearing the MIL/DTC
Diagnostic Aids

If the condition is intermittent, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table:

  1. Verifies that the fault is present.

  2. If DTC P0112 can be repeated only by duplicating the Failure Records conditions. Refer to Temperature vs Resistance table. The table may be used to test the IAT sensor at various temperatures in order to evaluate the possibility of a shifted sensor that may be shorted above or below a certain temperature. If this is the case, replace the IAT sensor. If the IAT sensor appears to be OK, the fault is intermittent refer to Diagnostic Aids.

  3. The new PCM must be programmed.

DTC P0112 IAT Sensor Circuit Low Voltage

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the IAT parameter.

Does the scan tool indicate the parameter is more than specified value?

135°C (275°F)

Go to Step 4

Go to Step 3

3

Operate vehicle within Failure Records conditions.

Does scan tool indicate DTC P0112 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the IAT sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the IAT parameter.

Does the scan tool indicate the parameter is less than the specified value?

-37°C (-34°F)

Go to Step 6

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Test the signal circuit of the IAT sensor for a short to ground. Refer to Circuit Testing , and to Wiring Repairs in Wiring Systems.

Did you find, and correct the condition?

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Go to Step 8

Go to Step 7

6

Replace the IAT sensor. Refer to Intake Air Temperature (IAT) Sensor Replacement .

Did you complete the replacement?

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Go to Step 8

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7

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .

Did you complete the replacement?

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Go to Step 8

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8

  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run, and pass?

--

Go to Step 9

Go to Step 2

9

With a scan tool, observe the stored information, Capture Info

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK