P0404

Schematic:

CIRCUIT DESCRIPTION
The ability of the PCM to control the EGR valve is verified with this test. The PCM calculates an error based on the difference between the actual EGR position and the desired EGR position. The PCM sets this DTC if the error is too great.

CONDITIONS FOR RUNNING THE DTC
^ The ignition voltage is more than 11.7 volts.
^ The desired EGR position is more than 0 percent.

CONDITIONS FOR SETTING THE DTC
^ The difference between the desired EGR position and the actual EGR position is more than 20 percent.
^ The failure counter is more than a predetermined value.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM disables the EGR for the ignition cycle.
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive drive cycle the diagnostic runs and fails.
^ The PCM records the operating conditions the first time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the Malfunction Indicator Lamp (MIL) OFF after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

DIAGNOSTIC AIDS

IMPORTANT:
^ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.
^ For any test that requires probing the PCM or a component harness connector, use the J 35616-A connector test adapter kit. Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Diagrams.

For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

TEST DESCRIPTION

Steps 1 - 10:

Steps 11 - 21:

The numbers below refer to the step numbers on the Diagnostic Table.
2. This step determines if the EGR valve can be commanded open.
3. Excessive resistance in the EGR control circuit or the EGR ground circuit will result in the EGR not responding correctly to the commanded EGR position.
4. This step tests the EGR Valve control circuit.
5. This step tests the EGR Valve ground circuit.
6. Excessive resistance in the control circuit or the ground circuit will cause this DTC to set. With the EGR commanded to 100% the test lamp should light with full intensity. Connect the test lamp across the battery terminals and compare the test lamp intensity to the EGR control circuit intensity.