P0112

P0112-INTAKE AIR TEMPERATURE SENSOR CIRCUIT LOW

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

Theory of operation

The Intake Air Temperature (IAT) sensor is a variable resistor that measures the temperature of the engine coolant. The Powertrain Control Module (PCM) supplies 5 Volts to the IAT signal circuit and supplies a ground to the low reference circuit.

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

- Set Condition:
When the Inlet Air Temp Sensor Signal circuit voltage is less than the minimum acceptable value. One trip failure. Three good trips to clear the MIL.





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

1. ACTIVE DTC
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 can result in possible serious or fatal injury.

NOTE: Diagnose and repair any system voltage DTCs before continuing with this test.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

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 MAP/IAT Sensor harness connector.
3. Ignition on, engine not running.
4. With the 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 MAP/IAT Sensor and Powertrain Control Module connectors. If OK, replace the MAP/Intake Air Temperature Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. IAT SIGNAL SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance between ground and the IAT Signal circuit in the MAP/IAT Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the IAT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. IAT SIGNAL SHORTED TO THE SENSOR GROUND CIRCUIT
1. Measure the resistance between the IAT Signal circuit and the Sensor ground circuit in the MAP/IAT Sensor harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short between the Sensor ground circuit and the IAT Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 5

5. EXCESSIVE RESISTANCE IN THE IAT SIGNAL CIRCUIT
1. Measure the resistance of the IAT Signal circuit between the Intake MAP/IAT Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the open or excessive resistance in the IAT Signal circuit.
- 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 MAP/IAT 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. Verify that there is good pin to terminal contact in the MAP/IAT Sensor and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

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

No

- Replace and program the Powertrain Control Module. PCM/ECM Reprogramming.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.