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 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 10-16 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
Inspect for the following condition:
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.
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies that the malfunction is present.
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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.
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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. Does the test lamp illuminate? | -- | ||||||
6 |
Is Actual EGR Position at the specified value? | 100% | ||||||
7 |
Did you find and correct the condition? | -- | ||||||
8 |
Does the test lamp illuminate? | -- | ||||||
9 |
Did you find and correct the condition? | -- | ||||||
10 |
Did you find and correct the condition? | -- | ||||||
11 |
Did you find and correct the condition? | -- | ||||||
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 |
Did you find and correct the condition? | -- | ||||||
Did you find and correct the condition? | -- | |||||||
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 |
