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 provide an overview of each diagnostic category. |
DTC Descriptor
DTC P040F: Exhaust Gas Recirculation (EGR) Temperature Sensor 1-2 CorrelationDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
EGR Temperature Sensor 1 Signal | P040C | P040D, P040F | P040D | P040F |
EGR Temperature Sensor 1 Low Reference | -- | P040D, P040F | -- | P040F |
EGR Temperature Sensor 2 Signal | P041C | P041D, P040F | P041D | P040F |
EGR Temperature Sensor 2 Low Reference | -- | P041D, P040F | -- | P040F |
Typical Scan Tool Data
Circuit | Short to Ground | Open/High Resistance | Short to Voltage |
|---|---|---|---|
Operating Conditions: Engine Running Parameter Normal Range: -40 to +900°C (-40 to +1652°F) | |||
EGR Temperature Sensor 1 Signal | 900°C (1652°F) | -40°C (-40°F) | -40°C (-40°F) |
EGR Temperature Sensor 1 Low Reference | -- | -40°C (-40°F) | -- |
EGR Temperature Sensor 2 Signal | -900°C (-1588°F) | -40°C (-40°F) | -40°C (-40°F) |
EGR Temperature Sensor 2 Low Reference | -- | -40°C (-40°F) | -- |
Circuit/System Description
The exhaust gas recirculation (EGR) temperature sensors are variable resistors that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the signal circuit and a ground for the low reference circuit. The ECM uses this rationality diagnostic to determine if the input from the EGR temperature sensor 1 or EGR temperature sensor 2 is skewed. The ECM will compare the temperature difference between the 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 greater than -7°C (+20°F). |
| • | DTC P040F runs once per key cycle within the above enabling conditions. |
Conditions for Setting the DTC
| • | The ECM detects a temperature difference of greater than 10°C (50°F) between EGR temperature sensors 1 and 2. |
| • | This DTC runs once per key cycle when the above condition is 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 . |
| • | 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
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: Determine the ambient temperature by using an accurate thermometer.
- If the ignition has been OFF for greater than 10 hours, determine which EGR temperature sensor is skewed by comparing EGR temperature Sensor 1 and 2 parameters to the ambient temperature with a scan tool. The readings should be within 11°C (20°F) of each other, and also the ambient temperature.
- Engine running, observe the scan tool EGR temperature Sensor 1 and 2 parameters. The readings should be between -39 to +400°C (-38 to +752°F), depending on the current ambient temperature and the vehicle operating conditions
- Engine running, observe the DTC information with a scan tool. DTC P040F should not set.
- 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.
- Ignition OFF, disconnect the harness connector at the affected ECT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal B and ground.
- Ignition ON, verify the scan tool EGR temperature sensor parameter is colder than -39°C (-40°F).
- 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 warmer than 890°C (1634°F).
- If all circuits test normal, test or replace the affected EGR temperature sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
Component Testing
Measure and record the resistance of the EGR temperature sensor 1 and compare those measurements to the Temperature Versus Resistance .
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
