Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM. The PCM compares Actual EGR Position with Desired EGR Position when the valve is commanded open. If Actual EGR Position varies more than 15 percent from Desired EGR position when the PCM is commanding the EGR valve opened, DTC P0404 will set.
Conditions for Running the DTC
System voltage is between 10 volts and 16 volts.
Conditions for Setting the DTC
| • | Desired EGR does not equal 0. |
| • | Actual EGR position varies more than 15 percent from Desired EGR Position. |
| • | The above conditions are present for more than 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has 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
Check for the following conditions:
| • | Excessive deposits on the EGR Pintle or seat -- Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick. |
| • | Poor connection at PCM or EGR valve -- Inspect harness connectors for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection |
| • | Damaged harness -- Inspect the wiring harness for damage. If the harness appears to be OK, connect a Digital Multimeter and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the display will indicate the location of the malfunction. |
If the DTC cannot be duplicated and is determined to be intermittent, reviewing the Failure Records can be useful in determining when the DTC was last set. Also refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
Verifies that the malfunction is present.
-
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, check for a poor connection at the PCM or the EGR valve. If the connections are OK and DTC P0404 continues to set, replace the EGR valve.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||
|
Important: : If any of the following DTCs are set, diagnose the other DTC first.
Does Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||||||
Does the scan tool indicate DTC P0404 failed this ignition? | -- | Go to Diagnostic Aids | ||||||
4 |
Is the voltage at the specified value? | 5 V | ||||||
5 | Probe the EGR pintle position signal circuit at the EGR valve harness connector with a test lamp connected to battery positive voltage. Is the test lamp on? | -- | ||||||
6 |
Is Actual EGR position at the specified value? | 100 percent | ||||||
7 |
Was a problem found? | -- | ||||||
8 |
Is the test lamp on? | -- | ||||||
9 |
Was a problem found? | -- | ||||||
10 |
Was a problem found? | -- | ||||||
11 |
Was a problem found? | -- | ||||||
12 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Is the action complete? | -- | -- | |||||
13 | Locate and correct the short to ground in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||
14 |
Was a problem found? | -- | ||||||
Was a problem found? | -- | |||||||
16 |
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .Is the action complete? | -- | -- | |||||
17 |
Does the scan tool indicate DTC P0404 failed this ignition? | -- | System OK |
