GM Service Manual Online
For 1990-2009 cars only

Object Number: 29578  Size: LF
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice
Engine Controls Components
EGR Control Pressure/BARO, IAT, ECT, and Boost Pressure Sensors
OBD II Symbol Description 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, sensor resistance becomes less and voltage drops. This is a type B DTC.

Conditions for Setting the DTC

    • Engine operating for 8 minutes.
    • IAT less than or equal to -40°C (-40°F).
    • Conditions met for 2 seconds.

Action Taken When the DTC Sets

    • The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails.
    • The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure Record will be updated.

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 when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.
    • Use of a Scan Tool

Diagnostic Aids

The scan tool displays intake air temperature in degrees centigrade. Refer to Intermittent in Section 2. A skewed sensor could result in poor driveability complaints.

Test Description

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 faulty PCM.

Step

Action

Value(s)

Yes

No

1

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

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

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Scan tool connected.
  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?

-40°C (-40°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 IAT greater than or equal to the specified value?

151°C (304°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 a IAT greater than or equal to the specified value?

151°C (304°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 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 faulty IAT sensor. Refer to Intake Air Temperature Sensor Replacement

Is the action complete?

--

Go to Step 12

--

11

Replace the faulty PCM.

Important:  If the PCM is faulty, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming

Is the action complete?

--

Go to Step 12

--

12

  1. Using the Scan Tool, select DTC, Clear Info.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

--

Go to Step 13

--

13

Using the Scan Tool, select Capture Info, Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC Table

System OK