GM Service Manual Online
For 1990-2009 cars only

Object Number: 64735  Size: MF
Engine Controls Components
Sensor Controls
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Intake Air Temperature (IAT) sensor is a thermister that controls signal voltage to the PCM. When the air is cold, the sensor resistance is high, therefore the PCM will see a high signal voltage. As air warms, the sensor resistance becomes less and the voltage drops. This is a type B DTC.

Conditions for Setting the DTC

    • The engine has been operating for 8 minutes.
    • The IAT is less than or equal to -40°C (-40°F).
    • The conditions were met for 2 seconds.

Action Taken When the DTC Sets

A possible poor performance problem may exist during cold weather operation.

Conditions for Clearing the MIL/DTC

    • The PCM will turn the MIL off after three consecutive trips without a fault condition.
    • A History DTC will clear after forty consecutive warm-up cycles during which the diagnostic does not fail (the coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle).
    • Use of a Scan Tool will clear the DTC codes.

Diagnostic Aids

The scan tool displays intake air temperature in degrees centigrade. Refer to Intermittent Conditions . A skewed sensor could result in poor driveability complaints. Refer to Temperature vs Resistance .

Test Description

The number(s) below refer to the step number(s) on the Diagnostic Table.

  1. This step determines if P0113 is a hard failure or an intermittent condition.

  2. This step will determine if there is a wiring problem or a malfunctioning PCM.

Step

Action

Value(s)

Yes

No

1

Important: Before clearing the DTCs, use the scan tool Capture Info in order to record the Freeze Frame and the failure records for reference, as the data will be lost when the Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Connect the scan tool.
  2. Start the engine.
  3. Monitor the IAT display on scan tool.

Does the IAT display a temperature colder than or equal to the specified value?

-30°C (-22°F)

Go to Step 3

Go to Step 5

3

  1. Turn the engine OFF.
  2. Turn the ignition ON.
  3. Disconnect the IAT sensor connector.
  4. Jumper the IAT harness terminals together.

Does the scan tool display an IAT greater than or equal to the specified value?

151°C (303°F)

Go to Step 6

Go to Step 4

4

Jumper the IAT sensor signal circuit to a known good ground.

Does the scan tool display an IAT greater than or equal to the specified value?

151°C (303°F)

Go to Step 7

Go to Step 8

5

DTC is intermittent. If no other DTCs are stored, refer to Diagnostic Aids.

Are than any other DTCs stored?

--

Go to the Applicable DTC Table

Go to Diagnostic Aids

6

Inspect the sensor connector and the PCM connector for a proper connection.

Was a problem found?

--

Go to Step 9

Go to Step 10

7

Check the IAT sensor ground circuit for an open between the IAT sensor and the PCM.

Was a problem found?

--

Go to Step 9

Go to Step 11

8

Check the IAT sensor signal circuit for an open between the IAT sensor and the PCM.

Was a problem found?

--

Go to Step 9

Go to Step 11

9

Repair the circuit as necessary.

Is the action complete?

--

Go to Step 12

--

10

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

Is the action complete?

--

Go to Step 12

--

11

Replace the PCM.

Important: The new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 12

--

12

  1. Use the Scan Tool in order to select DTC, Clear Info.
  2. Start the engine.
  3. Allow the engine to idle at the normal operating temperature.
  4. Select DTC, Specific, then enter the DTC number which was set.
  5. Operate the vehicle until the Scan Tool indicates that the diagnostic Ran.

Does the Scan Tool indicate that this diagnostic Passed?

--

Go to Step 13

--

13

Use the Scan Tool in order to select Capture Info, Review Info.

Are there any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC Table

System OK