P0111

P0111-INTAKE AIR TEMPERATURE SENSOR PERFORMANCE

For a complete wiring diagram, refer to the Wiring Information.





Theory of Operation

Intake Air Temperature Sensor performance looks at the outputs of three temperature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the ambient, engine coolant and intake air temperature sensors will be compared. If the engine coolant and ambient air temperature sensors agree and the intake air temperature does not agree, the intake air temperature sensor is declared as irrational. If declared irrational a second comparison will be done after a short drive cycle. The IAT Sensor is a variable resistor that functions as a normal two wire 5 volt sensor. The PCM supplies a 5 volt reference and a ground to the sensors low reference signal circuit.

- When Monitored:
With the engine off time greater than 480 minutes and ambient temperature greater than -7°C (19.4°F).

- Set Condition:
After a calibrated amount of cool down time, the Powertrain Control Module (PCM) compares the Ambient Air Temperature (AAT), Engine Coolant Temperature (ECT), and Intake Air Temperature (IAT) Sensor values. If one sensor value is not within 10°C (18°F) of the other temperature sensors for two consecutive trips, a DTC will set. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

Diagnostic Test

1. INTAKE AIR TEMPERATURE
1. Turn the ignition off.
2. If possible, allow the vehicle to sit with the ignition off for more than 480 minutes in an environment where the temperature is consistent and above -7°C (19.4°F).
3. Turn the ignition on.
4. With a scan tool, compare the AAT, ECT, and IAT sensor values.

Is the Intake Air Temperature Sensor value within 10°C (18°F) of the other two sensor values?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

No

- Go To

2. CHECK FOR HIGH RESISTANCE IN THE (K21) IAT SIGNAL CIRCUIT




1. Turn the ignition off.
2. Disconnect the Intake Air Temperature Sensor (IAT) harness connector.
3. Disconnect the Powertrain Control Module (PCM) C2 harness connectors.
4. Measure the resistance of the (K21) IAT Signal circuit between the Intake Air Temperature Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 3

No

- Repair the (K21) IAT Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

3. CHECK FOR HIGH RESISTANCE IN THE (K915) SENSOR GROUND CIRCUIT




1. Measure the resistance of the (K915) Sensor Ground circuit between the Intake Air Temperature Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

- Repair the (K915) Sensor Ground for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. INTAKE AIR TEMPERATURE SENSOR




1. Turn the ignition off.
2. Reconnect the PCM harness connectors.
3. Turn the ignition on.
4. With the scan tool, read the IAT Sensor signal voltage.
5. Connect a jumper between the (K915) Sensor Ground circuit and the (K21) IAT Signal circuit at the Intake Air Temperature Sensor harness connector.
6. Using the scan tool, read the IAT Sensor signal voltage.

NOTE:
The voltage should read 5.0 volts with the harness disconnected and 0 volts with the jumper in place.

Does the voltage read as described above?

Yes

- Replace the Intake Air Temperature Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Intake Air Temperature Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Perform any Technical Service Bulletins that may apply.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Replace and program the Powertrain Control Module (PCM). Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.