Circuit Description
The powertrain control module (PCM) monitors the exhaust gas recirculation (EGR) valve pintle position sensor input to ensure that the valve responds properly to commands from the PCM. When the valve is commanded open, the PCM compares the actual EGR valve position to the desired EGR valve position. If the actual EGR valve position is less than the desired EGR valve position by a calibrated amount, DTC P0404 is set.
Conditions for Running the DTC
| • | None of the following DTCs are set: |
| • | Throttle position (TP) sensor DTCs |
| • | Vehicle speed sensor (VSS) DTCs |
| • | Intake air temperature (IAT) sensor DTCs |
| • | Manifold absolute pressure (MAP) sensor DTCs |
| • | Engine coolant temperature (ECT) sensor DTCs |
| • | Crankshaft position (CKP) sensor DTCs |
| • | Mass air flow (MAF) sensor DTCs |
| • | Idle speed DTCs |
| • | Misfire DTCs |
| • | Fuel injector fault DTCs |
| • | The system voltage is between 10 and 16 volts. |
Conditions for Setting the DTC
| • | The Actual EGR position is 15% less than the Desired EGR position. |
| • | The above conditions is present for longer than 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed. |
| • | The PCM disables the EGR for the rest of the ignition cycle. |
| • | The PCM stores the conditions which were present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns the MIL off during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC may be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Inspect 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. |
| • | A faulty connection at the PCM or the EGR valve. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, connect a digital multimeter (DMM) and test the circuit continuity while moving the connectors and wiring harnesses related to the EGR valve. A change in the display indicates the location of the malfunction. |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set.
Test Description
The number(s) below refer to the step number(s) 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 faulty connection at the powertrain control module (PCM) or the EGR valve. If the connections are OK and DTC P0404 continues to set, replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .
-
This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read-only memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||||||
|
Important: If any of the following DTCs are set, diagnose the other DTC first.
Does the Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||||||
Does the scan tool indicate DTC P0404 Failed This Ign? | -- | Go to Diagnostic Aids | ||||||
4 |
Does the voltage equal the specified value? | 5 V | ||||||
5 | Use a test lamp connected to B+ in order to probe the EGR pintle position signal circuit at the EGR valve harness connector. Does the test lamp illuminate? | -- | ||||||
6 |
Does the Actual EGR Position equal the specified value? | 100% | ||||||
7 |
Was a problem found? | -- | ||||||
8 |
Does the test lamp illuminate? | -- | ||||||
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 . Did you complete the repair? | -- | -- | |||||
13 | Locate and correct the short to ground in the EGR pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | -- | |||||
14 |
Was a problem found? | -- | ||||||
15 |
Was a problem found? | |||||||
|
Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Did you complete the repair? | -- | -- | ||||||
17 |
Does the scan tool indicate DTC P0404 Failed This Ign? | -- | System OK |
