P0405

DTC P0405

CIRCUIT DESCRIPTION
The exhaust gas recirculation (EGR) valve position sensor is installed on the EGR valve body together with the EGR valve control motor. The EGR valve position sensor changes output voltage according to EGR valve position. The EGR position sensor has the following circuits.
- 5 volts reference circuit
- Low reference circuit
- EGR valve position sensor signal circuit

The engine control module (ECM) supplies 5 volts to the EGR valve position sensor on the 5 volts reference circuit. The ECM also provides a ground on the low reference circuit. The EGR valve position sensor provides a signal to the ECM on the EGR valve position signal circuit, which is relative to the position changes of the EGR valve. The ECM monitors the EGR position sensor signals for voltage outside the normal range of the EGR position. If the ECM detects an excessively low EGR valve position signal voltage, this DTC will set.

Condition for Running the DTC
- DTCs P0403, P0406, P0642 and P0643 are not set.
- The battery voltage is between 10-16 volts.
- The ignition switch is ON.

Condition for Setting the DTC
- The ECM detects that the EGR position sensor signal voltage is less than 0.5 volts for longer than 3 seconds.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.
- The ECM limits fuel injection quantity within 70%.
- The ECM closes the EGR valve and holds to close position.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when the diagnostic runs and does not fail. (12,000 lbs GVW)
- The ECM turns OFF the MIL when the diagnostic runs and does not fail. (Except 12,000 lbs GVW)
- 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 after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
If an intermittent condition is suspected, the following may cause an intermittent:
- Poor connections
- Misrouted harness
- Rubbed through wire insulation
- Broken wire inside the insulation

Check for the following conditions:
- Poor connection at the ECM: Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "EGR Position Sensor" display on the scan tool with the ignition ON, engine OFF while moving connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

DTC P0405
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls Connector End Views or Engine Control Module (ECM) Connector End Views

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