P0404

DTC P0404

CIRCUIT DESCRIPTION
The engine control module (ECM) controls the EGR valve opening based on the atmospheric pressure, engine speed, engine coolant temperature, intake air temperature and fuel injection quantity. The ECM controls the EGR valve by controlling the EGR DC motor. The EGR valve position is detected by the EGR position sensor, and relayed to ECM.

If the ECM detects an excessively high EGR valve control duty cycle, this DTC will set. (Control Duty Signal Error DTC)

If the ECM detects a variance between the actual EGR position and desired EGR position for a calibrated amount of time while the EGR valve is commanded open, this DTC will also set. (Open Position Error DTC)

Condition for Running the DTC
Control Duty Signal Error DTC
- DTCs P0401, P0403, P0404, P0405, P0406, P0642, P0643 and P1404 are not set.
- The battery voltage is between 10-16 volts.
- The ignition switch is ON for 2 seconds.

Open Position Error DTC (12,000 lbs GVW)
- DTCs P0112, P0113, P0116, P0117, P0118, P0403, P0405, P0406, P0642, P0643, P2227, P2228 and P2229 are not set.
- The battery voltage is between 10-16 volts.
- The ignition switch is ON for 5 seconds.
- The engine coolant temperature (ECT) is between 149- 178 °F (65-92 °C).
- The intake air temperature (IAT) is between 19 -302 °F (-7-150 °C).
- The barometric pressure (BARO) is between 10.9 -17.4psi (75-120kPa).
- The desired EGR valve position does not vary more than 5%.

Condition for Setting the DTC
Control Duty Signal Error DTC
- The ECM detects that the EGR valve control duty signal is more than 70% for longer than 8 seconds.

Open Position Error DTC (12,000 lbs GVW)
- The ECM detects that the actual EGR valve position is 10% lower than the desired EGR valve position for longer than 8 seconds.

Action Taken When the DTC Sets
Control Duty Signal Error DTC
- 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.

Open Position Error DTC (12,000 lbs GVW)
- The ECM illuminates the MIL on the second consecutive driving cycle 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 on the second consecutive driving cycle when the diagnostic runs and fails.

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 after the key is cycled.
- 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
- A sticking or intermittently sticking EGR valve may set this DTC.

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

Check for the following conditions:
- Damaged harness: Inspect the wiring harness for damage. If the harness appears to be OK, observe the "EGR Current Position" display on the scan tool with engine running while moving connectors and wiring harness. A change in the display will indicate the location of the fault.

Test Description
The number below refers to the step number on the diagnostic table.
3. Operate the vehicle within the same conditions as when the DTC failed. If you can not duplicate this DTC, use the information in the Freeze Frame/Failure Records data can help to locate an intermittent condition.

DTC P0404
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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