DTC Descriptor
DTC P0403: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit
Diagnostic Fault Information
Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit Description
The control module tests the exhaust gas recirculation (EGR) system during deceleration. The control module does this by momentarily commanding the EGR valve to open while monitoring the signal circuit of the manifold absolute pressure (MAP) sensor. When
the EGR valve is opened, the control module will expect to see a predetermined increase in MAP. If the expected increase in MAP is not detected, the control module records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards
a calibrated fail threshold level. The number of EGR flow test counts required to exceed the fail threshold may vary according to the amount of detected EGR flow error.
The EGR valve position sensor is monitored by the control module. The 5-volt reference circuit, the low reference circuit, and the EGR valve position signal circuit are used by the control module to determine the EGR valve position. The control module
compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed.
The control module controls the EGR valve with a solid state device called a driver. The driver supplies the EGR solenoid with 12 volts that is pulse width modulated (PWM) through the EGR solenoid high control circuit. A ground path is provided
by the control module through the EGR solenoid low control circuit.
When the ignition switch is turned ON, the control module records the EGR Learned Minimum Position. The control module compares the EGR Learned Minimum Position parameter to the EGR Position Sensor parameter.
The control module has the ability to detect an electrical malfunction on the EGR solenoid control circuits.
Conditions for Running the DTC
| • | The engine is cranking or running. |
| • | The Ignition 1 Signal parameter is between 11-18 volts. |
Conditions for Setting the DTC
| • | The PCM detects an electrical malfunction in the EGR solenoid high control circuit or the EGR solenoid low control circuit. |
| • | The above condition is met for more than 20 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 MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (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 or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
With the ignition ON and the engine OFF, command the EGR from 0-100 percent. The EGR Position Sensor parameter should remain within 3 percent of the Desired EGR Position parameter.
Circuit/System Testing
- Disconnect the EGR valve harness connector and probe the EGR high control circuit with a test lamp connected to ground. Command the EGR valve from 0 percent to 10 percent and back to 0 percent. The test lamp should illuminate
when commanded to 10 percent.
| ⇒ | If the test lamp remains illuminated when commanded to 0 percent, test the EGR high control circuit for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, test the EGR high control circuit for an open, high resistance, or short to ground. If the circuit tests normal, replace the control module. |
- Connect a test lamp between the EGR high control circuit and the EGR low control circuit. Command the EGR valve from 0 percent to 10 percent and back to 0 percent. The test lamp should illuminate when commanded to 10 percent.
| ⇒ | If the test lamp illuminates when commanded to 10 percent, replace the EGR valve. |
| ⇒ | If the test lamp does not illuminate, test the EGR low control circuit for an open or high resistance. |
| ⇒ | If all circuits test normal, replace the control module. |
Repair Instructions
Important: Always perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
