GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1996 🢒 Seville 🢒 DTC 🢒 DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage

Object Number: 12979 Size: SF
Engine Controls Components
IAT/ ECT/ TP/ MAP and BBV Sensors
OBD II Symbol Description Notice
ESD Notice
ESD Notice

Circuit Description

The Intake Air Temperature sensor is a thermistor, or variable resistor, that varies resistance based on temperature. Low temperature will result in a high signal voltage. DTC P0113 sets when the PCM sees an IAT sensor signal of -37°C (-35°F) or less with engine operating conditions that should have raised IAT temperature.

Conditions for Setting the DTC

Test Conditions

    • DTCs P0101, P0102, P0117, and P0118 not set.
    • Engine speed 500 RPM or greater for 20 seconds.
    • Vehicle speed has been greater than 7 MPH for 5 seconds this engine run cycle.
    • MAF input 60 grams per second or less.
    • Vehicle speed 50 MPH or less.
    • Engine coolant temperature 0°C (32°F) or greater.

OR

Engine coolant temperature less than 0°C (32°F) and IAT at least 27°C less than engine coolant temperature.

Failure Condition

The IAT sensor reading is -37°C (-35°F) or lower.

Action Taken When the DTC Sets
    • PCM turns ON the SERVICE EMISSION SYSTEM message.
    • PCM substitutes ambient air temperature for IAT.
    • Transaxle shift adapts are maintained at current levels.
    •  The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
    •  The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

    •  The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
    •  A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
    •  A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

Diagnostic Aids

IAT sensors can be damaged by backfire in the intake manifold. If the vehicle has had more than one IAT sensor replaced, check for signs of backfire. Under severe cold weather conditions this DTC could set if the actual outside temperature (IAT) is below -37°C (-35°F) and the ECT is at least 27°C warmer than IAT.

Test Description

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

  1. If IAT sensor circuit is open, IAT display should read -37°C (-35°F) or less.

    2.

  2. Checking if PCM and wiring are functioning properly. Jumping the IAT Sensor Signal circuit to the IAT sensor ground circuit should cause IAT to read 147°C (247°F) or more.

    3.

  3. Checking for poor terminal contact at IAT sensor.

    4.

  4. When the IAT Sensor Signal circuit is grounded, IAT should read 147°C (247°F) or greater. This helps to determine if problem is in the IAT Sensor Signal circuit or the IAT sensor ground circuit.

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

  1. Connect a scan tool.
  2. Turn the key ON.
  3. View the IAT sensor display.

Is the temperature the same or less than the value specified?

-37°C (-35°F)

Go to Step 3

Fault not present. Refer to Diagnostic Aids

3

  1. Disconnect the IAT sensor.
  2. Jumper IAT sensor connector terminals A and B together.

Is the temperature the same or more than the value specified?

147°C (247°F)

Go to Step 4

Go to Step 5

4

  1. Check the terminal contact at the IAT sensor.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 10

5

Jumper IAT sensor signal terminal to ground.

Is the temperature the same or more than the value specified?

147°C (247°F)

Go to Step 6

Go to Step 7

6
  1. Record the fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C1.
  3. Remove the jumper.
  4. Using DMM J 39200 measure the resistance between PCM connector C1 terminal 71 and IAT sensor ground terminal.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 11

Go to Step 8

7
  1. Record the fluid life indexes, turn the key to OFF and wait 30 seconds.
  2. Disconnect PCM connector C2.
  3. Using DMM J 39200 measure the resistance between PCM connector C2 terminal 76 and IAT sensor signal terminal.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 11

Go to Step 9

8

Repair the open in the IAT sensor ground circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

9

Repair the open in the IAT signal circuit.

Is the repair complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

10

Replace the IAT sensor. Refer to IAT Sensor Replacement .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

11
  1. Check terminal contact at the PCM connector C1 terminal 71 and connector C2 terminal 76.
  2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 12

12

Replace the PCM. Refer to PCM Replacement/Programming .

Is the replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

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