P040C

DTC P040C or P040D

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provide an overview of each diagnostic category.

DTC Descriptors

DTC P040C
- Exhaust Gas Recirculation (EGR) Temperature Sensor 1 Circuit Low Voltage

DTC P040D
- Exhaust Gas Recirculation (EGR) Temperature Sensor 1 Circuit High Voltage

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 EGR temperature sensor signal circuit, and supplies a ground to the low reference circuit. When the EGR temperature sensor is cold, the sensor resistance is high. When the EGR temperature increases, the sensor resistance decreases. With high sensor resistance, the ECM detects a higher voltage on the EGR temperature signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the EGR temperature signal circuit.

Conditions for Running the DTC

P040C
* The engine is running.
* The coolant temperature is less than 150°C (302°F).
* The engine is not in regeneration.
* This DTC runs continuously when the above conditions are met.

P040D
* The engine is running.
* The coolant temperature is more than 150°C (302°F).
* This DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

P040C
* The ECM detects that the EGR sensor is colder than 800°C (1472°F).
* The condition exists for greater than 1 second.

P040D
* The ECM detects that the exhaust temperature sensor is warmer than 100°C (212°F).
* The condition exists for greater than 1 second.

Action Taken When the DTC Sets

DTCs P040C and P040D are Type A DTCs.

Conditions for Clearing the DTC

DTCs P040C and P040D are Type A DTCs.

Diagnostic Aids

* Inspect the EGR temperature sensor terminals for corrosion.
* A short to a separate 5-volt source occurs, this DTC will set.

Circuit/System Verification

1. Engine running, observe the scan tool EGR temperature Sensor 1 parameter. The reading should be within the normal range -38°C to +800°C (-36°F to +1472°F), depending on the current ambient temperature and the vehicle operating conditions.
2. Engine running, observe the DTC information with a scan tool. DTCs P040C or P040D should not be 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

1. Ignition OFF, disconnect the harness connector at the EGR temperature sensor 1.
2. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal A 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 1 parameter is colder than -30°C (+1,828°F).

^ If warmer more than the specified range, test the signal circuit terminal B 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 a good ground. Verify the scan tool EGR temperature parameter is warmer than 890°C (1634°F).

^ 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 the sensor. Refer to Component Testing for instructions.

Component Testing

Measure and record the resistance of the EGR temperature sensor 1 and compare those measurements to the Temperature Versus Resistance (EGR Temperature Sensors) Temperature Versus Resistance (Fuel Temperature Sensor) Temperature Versus Resistance (IAT Sensor 1) Temperature Versus Resistance (ECT Sensors) Temperature Versus Resistance (IAT Sensor 2) Temperature Versus Resistance (EGT Sensors).

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Engine Control Module Replacement