DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage. Buick GL7 (Export) 2000

For 1990-2009 cars

### 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 5.0 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 underhood air warms, the sensor resistance becomes lower causing the PCM to monitor a lower voltage. If the PCM detects an excessively high IAT sensor signal voltage, DTC P0113 will set.

### Conditions for Running The DTC

• | No active ECT, MAF sensor or VSS DTCs are present.

• | The vehicle speed is less than 56 km/h (35 mph).

• | The MAF is less than 12 gm/s.

• | The ECT is more than 60°C (140°F).

• | The engine has been running for at least 3 minutes.

### Conditions for Setting the DTC

• | The IAT signal voltage indicates an intake air temperature of less than -37°C (-35°F).

• | The above conditions are present for at least 20 seconds.

### Action Taken When the DTC Sets

• | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.

• | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

### Conditions for Clearing the MIL/DTC

• | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.

• | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using a scan tool.

### Diagnostic Aids

Inspect for the following conditions:

• | A poor connection at PCM. Inspect the harness connectors for the following conditions:

- | Backed-out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal-to-wire connections

• | Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

• | A damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the IAT display on the scan tool while moving the connectors and the wiring harnesses related to the IAT sensor. A change in the IAT display will indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems.

If DTC P0113 cannot be duplicated, the information included in the Failure Records data can be useful in determining the vehicle mileage since the DTC was last set.

### Test Description

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

1. Verifies that the fault is present.

2. If DTC P0113 can be repeated only by duplicating the Failure Records conditions, use the Temperature vs Resistance table to test the IAT sensor at various temperatures in order to evaluate the possibility of a shifted sensor that may be open 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.

3. Use a fused jumper during this test. If the IAT signal circuit is shorted to battery or ignition positive voltage the fuse in the jumper will open, indicating a short in the signal circuit.

4. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). If the PCM is replaced, the new PCM must be programmed.

#### DTC P0113 - IAT Sensor Circuit High Voltage

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

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

Is the IAT less than the specified value?

-37°C (-34°F)

Go to Step 4

Go to Step 3

3

1. With a scan tool, review and record the Failure Records data.
2. Operate the vehicle within the Failure Records conditions as noted.

Does the scan tool indicate DTC P0113 failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

Important: If a 5 volt reference DTC sets while the engine is running, repair the IAT signal circuit for a short to 5 volts.

1. Turn OFF the ignition.
2. Disconnect the IAT sensor.
3. Connect a 3 amp fused jumper between the signal circuit of the IAT sensor and the ground circuit of the IAT sensor.
4. Turn ON the ignition.
5. With a scan tool, observe the IAT parameter.

Is the IAT more than the specified value?

135°C (275°F)

Go to Step 6

Go to Step 5

5

1. Jumper the IAT signal circuit to ground.
2. With a scan tool, observe the IAT parameter.

Is the IAT more than the specified value?

135°C (275°F)

Go to Step 7

Go to Step 8

6 | Test the signal circuit of the IAT sensor for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10
7 | Test the ground circuit of the IAT sensor for a high resistance or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9
8 | Test the signal circuit of the IAT sensor for an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9
9 | Inspect for faulty IAT sensor ground or signal circuit connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12
10 | Inspect for a faulty connection at the IAT sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11
11 | Replace the IAT sensor. Refer to Intake Air Temperature Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | --
12 | Important: : The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | Go to Step 13 | --

13

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Failure Records conditions as noted.

Does the DTC reset?

--

Go to Step 2

System OK