VIN 6
DTC P040F
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provide an overview of each diagnostic category.
DTC Descriptor
DTC P040F
- Exhaust Gas Recirculation (EGR) Temperature Sensor 1-2 Correlation
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The exhaust gas recirculation (EGR) temperature sensors are variable resistors that measure the temperature of the exhaust gas at the inlet and outlet of the EGR cooler. The engine control module (ECM) supplies 5 volts to the temperature sensor signal circuit and a ground for the low reference circuit. The ECM uses this rationality diagnostic to determine if the input from EGR temperature sensor 1 or EGR temperature sensor 2 is skewed. The ECM will compare the temperature difference between EGR temperature sensor 1 and the EGR temperature sensor 2 to determine if the temperatures are within an acceptable operating range of each other.
Conditions for Running the DTC
* The engine has been OFF for more than 5 hours.
* The ambient temperature is warmer than -7°C (+20°F).
* DTC P040F runs once per key cycle within the above enabling conditions.
Conditions for Setting the DTC
* DTCs P040C, P040D, P041C or P041D are not set.
* The ECM detects a temperature difference of between 32-99°C (89.6-210.2°F) between EGR temperature sensors 1 and 2 for 3 seconds or longer.
* This DTC runs once per key cycle when the above conditions are met.
OR
* DTCs P040C, P040D, P041C, or P041D are not set.
* The ECM detects a temperature difference of greater than 99°C (210.2°F) between EGR temperature sensors 1 and 2.
* The vehicle is driven greater than 25 mph (40.2 kph) for greater than 10 minutes.
* This DTC runs once per key cycle when the above conditions are met.
Action Taken When the DTC Sets
DTC P040F is a Type B DTC.
Conditions for Clearing the DTC
DTC P040F is a Type B DTC.
Diagnostic Aids
* A slight to moderate resistance in either signal or low reference circuit can widen the spread between the two EGR temperature sensors and cause this DTC to set.
* An EGR temperature sensor that is skewed lower at various ambient temperatures, due to more resistance than is normal, can widen the spread between the two sensors and cause this DTC to set. Measure and record the resistance of both EGR temperature sensors 1 and 2 at ambient temperature. Compare those measurements to the Temperature Versus Resistance (Fuel Temperature Sensor) (Temperature Versus Resistance (Fuel Temperature Sensor)) Temperature Versus Resistance (ECT Sensors) (Temperature Versus Resistance (ECT Sensors)) Temperature Versus Resistance (IAT Sensor 1) (Temperature Versus Resistance (IAT Sensor 1)) Temperature Versus Resistance (IAT Sensor 2) (Temperature Versus Resistance (IAT Sensor 2)) Temperature Versus Resistance (EGT Sensors) (Temperature Versus Resistance (EGT Sensors)) Temperature Versus Resistance (EGR Temperature Sensors) (Temperature Versus Resistance (EGR Temperature Sensors)).
* Inspect both EGR temperature sensors terminals for corrosion and for poor connections. It is very important that a thorough inspection of the wiring and connectors be performed. Failure to fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
* EGR temperature sensors may fail while operating under extreme temperatures. Review the Freeze Frame/Failure Records to verify the failure criteria.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Important: Determine the ambient temperature by using an accurate thermometer.
1. To determine which EGR temperature sensor is skewed, ensure that the ignition has been OFF for greater than 5 hours. Install a scan tool and turn the ignition to ON. Observe the EGR Cooler Temp. Sen. 1 and EGR Cooler Temp. Sen. 2 parameters and compare them to ambient temperature. Depending on current ambient temperature and vehicle operation conditions, each sensor parameter should be between -32 to +899°C (-25.6 to +1,650°F). Each sensor parameter should also be less than 33°C (91°F) different from ambient temperature.
2. Engine running, observe the DTC information with a scan tool. DTC P040F should not set.
3. 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 data.
Circuit/System Testing
Important: If you are unable to determine which EGR temperature sensor is skewed, you must perform the Circuit/System Verification first.
1. Ignition OFF, disconnect the harness connector at the affected ECT sensor.
2. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal B and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, verify the scan tool EGR temperature sensor parameter is -33°C (-27.4°F) or colder.
• If warmer than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM.
4. Install a 3A fused jumper wire between the signal circuit terminal A and the low reference circuit terminal B. Verify the scan tool ECT parameter is 899°C (1,650°F) or warmer.
• 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 ECM.
5. If all circuits test normal, test or replace the affected EGR temperature sensor.
Component Testing
Measure and record the resistance of the EGR temperature sensor 1 and compare those measurements to the Temperature Versus Resistance (Fuel Temperature Sensor) (Temperature Versus Resistance (Fuel Temperature Sensor)) Temperature Versus Resistance (ECT Sensors) (Temperature Versus Resistance (ECT Sensors)) Temperature Versus Resistance (IAT Sensor 1) (Temperature Versus Resistance (IAT Sensor 1)) Temperature Versus Resistance (IAT Sensor 2) (Temperature Versus Resistance (IAT Sensor 2)) Temperature Versus Resistance (EGT Sensors) (Temperature Versus Resistance (EGT Sensors)) Temperature Versus Resistance (EGR Temperature Sensors) (Temperature Versus Resistance (EGR Temperature Sensors)).
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Engine Control Module Replacement (Service and Repair)
* Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 2 (Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 2)
* Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 1 (Exhaust Gas Recirculation Valve Temperature Sensor Replacement - Position 1)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming