P046C
DTC P046C
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 provides an overview of each diagnostic category.
DTC Descriptor
DTC P046C
- Exhaust Gas Recirculation (EGR) Position Sensor Performance
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The engine control module (ECM) uses the exhaust gas recirculation (EGR) position sensor to determine the position of the EGR valve. The ECM sends a reference voltage through the 5-volt reference circuit to the EGR position sensor. The ECM provides a voltage return path for the sensor through the low reference circuit. A variable voltage signal, based on the EGR valve position, is sent from the sensor to the ECM through the EGR position sensor signal circuit. The ECM compares the actual EGR position with the desired EGR position when the EGR valve is commanded open or closed.
Conditions for Running the DTC
* DTCs P0401, P0402, P0403, P0642, or P0643 are not set.
* The EGR valve is actively being controlled.
* DTC P046C runs continuously when the above conditions have been met.
Conditions for Setting the DTC
* The difference between the actual EGR position and the desired EGR position is more than 3 percent.
* The above condition is present for more than 5 seconds.
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 DTC
* The control module turns OFF the MIL after 3 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 diagnostic.
* Clear the MIL and the DTC with a scan tool.
Circuit/System Verification
Important: If you cannot duplicate the condition, 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.
1. Command the EGR valve to 10 percent. The EGR Position Variance parameter should remains less than 3 percent.
2. Engine running, observe the DTC information with a scan tool. DTC P046C 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 Records data.
Circuit/System Testing
Important: Perform the Circuit/System Verification before proceeding with the Circuit/System Testing.
1. Capture the information and clear the DTCs with a scan tool.
2. Turn OFF the ignition. Disconnect the EGR valve. Install the EN-48565 between the EGR valve and the harness connector.
3. Turn ON the ignition. Command the EGR valve to 50 percent and back to 0 percent. The EGR test harness lamp should turn ON between 10 percent and 50 percent, and turn OFF at 0 percent.
• If the lamp does not turn ON and OFF, test both motor control circuits for an open/high resistance, short to voltage, or short to ground. If the circuits test normal, replace the control module.
• If the lamp turns ON and OFF, replace the EGR valve.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
* Exhaust Gas Recirculation Valve Replacement
* Control Module References for replacement, setup, and programming Programming and Relearning Verification Tests