Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0111: Intake Air Temperature (IAT) Sensor Circuit PerformanceDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
IAT Sensor Signal | P0112 | P0111, P0113 | P0113¹ | P0111¹ |
Low Reference | P0101, P0103 | P0111, P0113 | P0113² | P0101, P0111 |
¹ Sensor damage may occur if the circuit is shorted to B+. ² Internal ECM damage may occur if the circuit is shorted to B+. | ||||
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine operating in Closed Loop. Parameter Normal Range: -40 to +135°C (-40 to +275°F) Varies with ambient temperature. | |||
IAT Sensor Signal | 135°C (275°F) | -40°C (-40°F) | -40°C (-40°F)¹ |
Low Reference | -- | -40°C (-40°F) | -40°C (-40°F)¹ |
¹ Internal ECM or sensor damage may occur if the circuit is shorted to B+. | |||
Circuit Description
The intake air temperature (IAT) sensor is an integral part of the mass air flow (MAF) sensor. The IAT sensor is a variable resistor that measures the temperature of the intake air. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and supplies a ground to the low reference circuit. The ECM monitors the performance of the IAT sensor within its typical operating range. If the ECM does not detect a predetermined change in the IAT during calibrated driving conditions, this DTC sets.
The following table illustrates the difference between temperature, resistance, and voltage:
IAT | IAT Resistance | IAT Signal Voltage |
|---|---|---|
Cold | High | High |
Warm | Low | Low |
Conditions for Running the DTC
Idle Test
| • | Before the ECM can report DTC P0111 failed, DTC P0101 must run and pass. |
| • | DTCs P0112, P0113, P0116, P0117, P0118, P0119, P0125, and P0128 are not set. |
| • | The engine coolant temperature (ECT) at engine start is less than 48°C (118°F). |
| • | The ECT is more than 65°C (149°F). |
| • | The vehicle speed is less than 10 km/h (6.3 mph). |
| • | DTC P0111 runs continuously once the above conditions are met for more than 2 seconds. |
Cruise Test
| • | Before the ECM can report DTC P0111 failed, DTC P0101 must run and pass. |
| • | DTCs P0112, P0113, P0116, P0117, P0118, P0119, P0125, and P0128 are not set. |
| • | The ECT at engine start is less than 65°C (149°F). |
| • | The vehicle speed is more than 60 km/h (37 mph). |
| • | The MAF is between 11-42 g/s. |
| • | Decel fuel cut-off (DFCO) is not active. |
| • | DTC P0111 runs continuously once the above conditions are met for more than 2 seconds. |
Conditions for Setting the DTC
Idle Test
| • | The ECM detects that the IAT increased less than 2°C (4°F). |
| • | The condition exists for a total of 16 seconds or 4 events of more than 4 seconds each. |
Cruise Test
| • | The ECM detects that the IAT decreased less than 2°C (4°F). |
| • | The condition exists for more than 1 minute or 16 events of more than 4 seconds each. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 4 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | If the vehicle has sat overnight, the IAT sensor and the ECT sensor values should display within 3°C (5°F). |
| • | High resistance on either the IAT sensor signal circuit or the IAT sensor low reference circuit could set a DTC. |
| • | The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views . |
| • | Use the J 35616-A/BT-8637 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
- Verify that the following DTCs are not set: P0101, P0112, P0113, P0116, P0117, P0118, P0119, P0125, P0128.
- Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. DTC P0111 should not set.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Circuit/System Testing
- Ignition OFF, disconnect the MAF/IAT sensor.
- Ignition ON, verify that the IAT sensor parameter is at -40°C (-40°F).
- Ignition OFF, remove the ECM/TCM fuse from the underhood fuse block.
- Test for less than 5 ohms between the low reference circuit and the ECM housing.
- Ignition OFF, install the ECM/TCM fuse to the underhood fuse block.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the IAT sensor and verify the IAT sensor parameter is greater than 132°C (270°F).
- If all circuits/connections test normal, test or replace the MAF/IAT sensor.
| ⇒ | If greater than -40°C (-40°F), test the signal circuit of the IAT sensor for a short to ground. If the circuit/connections test normal, replace the ECM. |
Notice: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
| ⇒ | If greater than 5 ohms, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If less than 132°C (270°F), test the signal circuit of the IAT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector of the IAT sensor.
- Test the IAT sensor by varying the sensor temperature while monitoring the sensor resistance. Compare the readings with the Temperature Versus Resistance - Intake Air Temperature Sensor table and verify that the resistance is within 5 percent of the specification.
Important: A thermometer can be used to test the sensor of the vehicle.
| ⇒ | If the resistance vs temperature is not within 5 percent, replace the IAT sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
