| Table 1: | EGR Valve Terminal (Pin) Identification |
Circuit Description
The DTC P0403 Exhaust Gas Recirculation (EGR) Solenoid Control Circuit diagnostic monitors the electrical circuitry of the EGR valve. The EGR system controls the formation of oxides of nitrogen (NOx) emissions by recirculating the exhaust gases into the combustion chamber. The EGR valve is a stepper motor design. The stepper motor moves a spring loaded plunger that controls the flow of exhaust gases into the intake manifold. The plunger movement is controlled by the powertrain control module (PCM). By turning the stepper motor in different directions, the PCM controls the opening of the exhaust gas passage to the intake manifold. The stepper motor has 4 coil windings that control the motor movement. The DTC P0403 diagnostic monitors the electrical circuits of the 4 coils.
Conditions for Running the DTC
| • | The intake air temperature (IAT) is at least -14°C (7°F) |
| • | The engine is running |
Conditions for Setting the DTC
The voltage observed by the PCM on the EGR valve coil control circuits is lower than expected.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) after 2 consecutive ignition cycles in which the diagnostic runs with the fault active. |
| • | The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer. |
Conditions for Clearing the MIL/DTC
| • | The MIL turns OFF after 3 consecutively passing trips without a fault present. |
| • | A history DTC clears after 40 consecutive warm-up cycles without a fault. |
| • | Perform the scan tool Clear DTC Information function in order to clear the DTC. |
Diagnostic Aids
A normal engine operating temperature is specified as 80°C (176°F) or more.
Check for the following conditions:
| • | An incorrect PCM can cause DTC P0403 to set. Verify that the correct PCM is installed in the vehicle as required for proper emission certification. |
| • | A faulty electrical connection at the PCM. |
An intermittent malfunction may be caused by a fault in the EGR control system electrical circuits. Inspect the wiring harness and the components for an intermittent condition. Refer to Intermittent Conditions .
If a DTC P0403 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.
Use the following table in order to locate the correct terminals to test during diagnosis. The table layout corresponds to the pin location of the EGR valve electrical terminals.
Connector Lock Tab | ||
Pin 3 | Pin 2 | Pin 1 |
Pin 6 | Pin 5 | Pin 4 |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and to store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
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This step checks the ignition positive voltage supply to the EGR coils.
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This step tests the operation of the EGR valve. If the EGR valve responds to commands from the scan tool and the engine reacts to the valve opening, the system is operating normally at this time. The duty cycle output control of the EGR is disabled by the PCM when any DTCs are stored and when the engine temperature is less than 80°C (176°F).
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This step checks for a fault in the EGR coil control circuits.
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Clearing the DTCs by removing the DOME fuse also clears the PCM long term memory. Using the scan tool to clear DTCs leaves the long term memory active. DTC emitting diagnostics may not run to completion as expected unless the long term memory is cleared. Removal of the DOME fuse also clears the time display of the radio. The DTC P0403 diagnostic can be monitored on the scan tool under the Not Ran Since Code Cleared selection in the DTC Information menu. If a DTC P0403 appears in the Not Ran Since Code Cleared list, the DTC P0403 diagnostic has not yet run. When the DTC P0403 does not appear in the Not Ran Since Code Cleared list, the DTC P0403 diagnostic has run. If the MIL is NOT illuminated, and there is no Pending DTC Status in DTC Information, the DTC P0403 diagnostic has passed. The DTCs MUST be cleared in order to view the Current Status of the Not Ran Since Code Cleared list. DO NOT forget that the Not Ran Since Code Cleared list only indicates that the test has run, not whether the test passed or failed. The DTC Information screen must be checked for Current or Pending status, in order to determine the outcome of the diagnostic test involved.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||||
Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | ||||||||||
Does the test lamp illuminate on both circuits? | -- | Go to Step 3 | Go to Step 6 | |||||||||
3 |
Does the EGR valve pass all the resistance tests? | 20-24 ohms at 20°C (68°F) | Go to Step 4 | Go to Step 7 | ||||||||
Does the engine run rough or stall? | -- | Go to Diagnostic Aids | Go to Step 5 | |||||||||
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 | |||||||||
6 | Repair the open in the ignition positive voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the action? | -- | Go to Step 10 | -- | ||||||||
7 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||
8 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||||
9 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||||
Does the DTC run and pass? | -- | Go to Step 11 | Go to Step 2 | |||||||||
11 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||
