PRE-RELEASE
DTC P0111 (LF1)
| DTC P0111 (LF1) |
| Diagnostic Instructions |
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Perform the
Diagnostic System Check - Vehicle
prior to using this diagnostic procedure.
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Review
Strategy Based Diagnosis
for an overview of the diagnostic approach.
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Diagnostic Procedure Instructions
provides an overview of each diagnostic category.
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| DTC Descriptor |
DTC P0111
Intake Air Temperature (IAT) Sensor Performance
| Diagnostic Fault Information |
IAT Sensor
| Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
| IAT Sensor Signal | P0112, P0114 | P0111, P0113, P0114 | P0113*, P0114 | P0111 |
| Low Reference | - | P0111, P0113, P0114 | P0113*, P0114 | P0111 |
| *Internal ECM or sensor damage may occur if the circuit is shorted to B+. | ||||
| Typical Scan Tool Data |
IAT Sensor
| Circuit | Short to Ground | Open or High Resistance | Short to Voltage |
| Operating Conditions: Engine Running Parameter Normal Range: Varies with ambient temperature | |||
| IAT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F)* |
| Low Reference | - | -40°C (-40°F) | -40°C (-40°F)* |
| *Internal ECM or sensor damage may occur if the circuit is shorted to B+ | |||
| Typical Scan Tool Data |
ECT Sensor
| Circuit | Short to Ground | Open or High Resistance | Short to Voltage |
| Operating Conditions: Engine Running Parameter Normal Range: Varies with coolant temperature | |||
| ECT Sensor Signal | 150°C (302°F) | -40°C (-40°F) | -40°C (-40°F)* |
| Low Reference | - | -40°C (-40°F) | -40°C (-40°F)* |
| *Internal ECM or sensor damage may occur if the circuit is shorted to B+ | |||
| Circuit/System Description |
The intake air temperature (IAT) sensor is integrated with the mass air flow (MAF) sensor. It is a variable resistor that measures the temperature of the air entering the engine. The IAT sensor has a signal circuit and a low reference circuit. The engine control module (ECM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit.
| IAT | IAT Resistance | IAT Signal Voltage |
| Cold | High | High |
| Warm | Low | Low |
| Conditions for Running the DTC |
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DTCs P0112, P0113, P0117, P0118 are not set.
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The vehicle has been OFF at least 8 hours.
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The ignition is ON.
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This DTC runs once per ignition cycle when the enabling conditions are met.
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| Conditions for Setting the DTC |
The ECM determines the absolute difference between IAT start-up temperature and the ECT start-up temperature is greater than 20°C (36°F).
| Action Taken When the DTC Sets |
DTC P0111 is a Type B DTC.
| Conditions for Clearing the DTC |
DTC P0111 is a Type B DTC.
| Diagnostic Aids |
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An IAT sensor that is skewed, due to more resistance than is normal, can widen the spread between the 2 sensors and cause this DTC to set. Measure and record the resistance of the IAT sensor at various ambient temperatures, and then compare those measurements to the Temperature vs. Resistance Table. Refer to
Temperature Versus Resistance - Intake Air Temperature Sensor
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A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT.
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Inspect the mass air flow/intake air temperature sensor terminals for corrosion.
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| Reference Information |
Schematic Reference
Engine Controls Schematics (3.0L (LF1)) Engine Controls Schematics (2.8L (LAU))
Connector End View Reference
Component Connector End Views
Electrical Information Reference
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Circuit Testing
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Connector Repairs
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Testing for Intermittent Conditions and Poor Connections
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Wiring Repairs
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DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
| Circuit/System Verification |
| Note | ||
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Perform Step 1 of this verification procedure only if the ignition has been OFF for 8 hours or more. |
| 1. |
Ignition ON, observe the following scan tool parameters. The readings should be within 20°C (36°F) of each other.
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Start-Up IAT
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Start-Up ECT
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| 2. |
Engine running, observe the scan tool IAT sensor parameter. The reading should be between -38 and +149 °C (-36 and +300 °F), depending on the current ambient temperature and the vehicle operating conditions.
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| 3. |
Operate the vehicle within the conditions for running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
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| Circuit/System Testing |
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Ignition OFF, disconnect the harness connector at the B75B mass air flow/intake air temperature sensor.
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Remove the fuse that supplies B+ to terminal 52 X1 of the ECM.
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Ignition OFF, all systems OFF. It may take up to for 2 minutes for all vehicle systems to power down. Test for less than 5 Ω between the low reference circuit terminal D and ground.
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If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F).
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If warmer than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
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Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool IAT Sensor parameter is warmer than 149°C (300°F). |
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| 8. |
If colder than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
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| 9. |
If all circuits test normal, test or replace the B75B mass air flow/intake air temperature sensor.
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| Component Testing |
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Ignition OFF, disconnect the harness connector at the B75B mass air flow/intake air temperature sensor.
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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 . The resistance values should be in range of the table values. |
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If not within the specified range, B75B mass air flow/intake air temperature sensor.
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| Repair Instructions |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LAU)
Mass Airflow Sensor with Intake Air Temperature Sensor Replacement (LF1)
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Control Module References
for ECM replacement, setup, and programming
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