P0112

P0112-INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOW





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.

- When Monitored:
With the ignition on and the battery voltage greater than 10.4 Volts.

- Set Condition:
The Powertrain Control Module (PCM) detects that the Intake Air Temperature (IAT) Sensor input voltage is below the minimum acceptable value.





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

1. DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE
1. Start the engine and allow it to reach normal operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2. Using the scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

- Go To 2

No

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

2. IAT SENSOR
1. Turn the ignition off.
2. Disconnect the IAT Sensor harness connector.
3. Ignition on, engine not running.
4. With a scan tool, read IAT voltage.

NOTE: The sensor voltage should be approximately 5.0 volts (plus or minus.1 volt) with the connector disconnected.

Does the scan tool display the voltage as described above?

Yes

- Verify that there is good pin to terminal contact in the Intake Air Temperature Sensor and Powertrain Control Module connectors. Replace the Intake Air Temperature Sensor if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (K21) IAT SIGNAL CIRCUIT SHORTED TO GROUND




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

Is the resistance above 100 Ohms?

Yes

- Go To 4

No

- Repair the (K21) IAT Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

4. (K21) IAT SIGNAL CIRCUIT SHORTED TO THE (K915) SENSOR GROUND CIRCUIT




1. Measure the resistance between the (K21) IAT Signal circuit and the (K915) Sensor Ground circuit in the IAT Sensor harness connector.

Is the resistance above 100 Ohms?

Yes

- Go To 5

No

- Repair the (K21) IAT Signal circuit for a short to the (K915) Sensor Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. (K21) IAT SIGNAL CIRCUIT OPEN CIRCUIT OR HIGH RESISTANCE




1. Measure the resistance of the (K21) IAT Signal circuit between the IAT Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

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

6. 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.