P0404

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) monitors the Exhaust Gas Recirculation (EGR) valve pintle position input to ensure that the valve responds properly to commands from the PCM. The PCM compares the EGR position sensor with the desired EGR position when the valve is commanded open. If the difference between the EGR position sensor and desired EGR position is more than 10 percent DTC P0404 will set.

CONDITIONS FOR RUNNING THE DTC
^ The ignition voltage is more than 11.7 volts.
^ The commanded EGR position is more than 0 percent.
^ The EGR flow test is not active.
^ The desired EGR position does not change more than 20 percent.

CONDITIONS FOR SETTING THE DTC
^ The vehicle must be driven.
^ The difference between the desired EGR position and the EGR position sensor is more than 10 percent.
^ The condition is present for more than 13 seconds

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in 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.
^ The PCM disables the EGR for the ignition cycle.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
^ The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using a scan tool.

DIAGNOSTIC AIDS
^ Inspect for excessive deposits on the EGR pintle or seat. Remove the EGR valve and inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.
^ If the problem is intermittent, refer to Intermittent Conditions. Intermittent Conditions

TEST DESCRIPTION

Steps 1-2:

Steps 3-12:

Steps 13-25:

The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the malfunction is present.
3. If DTC P0404 will only set under certain conditions, the malfunction may be intermittent. Refer to Diagnostic Aids. If an intermittent wiring problem is not present, test for a faulty connection at the PCM or the EGR valve. If the connections are OK and DTC P0404 continues to set, replace the EGR valve.
6. When using the scan tool to increment the EGR valve, increment the valve to 10 percent then to 0 percent. Repeat this process to see if the test lamp turns ON then OFF. If the test lamp does not turn OFF when the EGR valve is commanded to 0 percent the EGR solenoid high control circuit is shorted to voltage.
7. When using the scan tool to increment the EGR valve, increment the valve to 10 percent then to 0 percent. Repeat this process to see if the test lamp turns ON then OFF. If the test lamp does not turn OFF when the EGR valve is commanded to 0 percent the EGR solenoid high control circuit is shorted to voltage. If the test lamp does not turn ON when the EGR valve is commanded to 10 percent the EGR solenoid high control is open or shorted to ground.