Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor circuit is open or shorted. If the PCM detects an excessively low EGR Feedback signal voltage, DTC P0405 will set.
Conditions for Running the DTC
System voltage is more than 9 volts.
Conditions for Setting the DTC
| • | EGR Feedback is less than 0.14 volt at any time. |
| • | The condition is 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
| • | Poor connection at PCM or EGR valve -- Inspect the harness connectors for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| • | 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 P0405 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.
-
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 DTC P1635 5 Volt Reference Circuit is also set, perform that diagnostic first.
Does Desired EGR Position remain close to Actual EGR Position at all commanded positions? | -- | |||||||||
Does the scan tool indicate DTC P0405 failed this ignition? | -- | Go to Diagnostic Aids | ||||||||
4 |
Does the voltage measure near the specified value? | 5 V | ||||||||
5 | Probe the EGR valve pintle position signal circuit at the EGR valve harness connector with a test lamp connected to B+. Does the test lamp illuminate? | -- | ||||||||
6 |
Is Actual EGR Position near the specified value? | 100 percent | ||||||||
7 |
Did you find and correct the condition? | -- | ||||||||
8 |
Does the test lamp illuminate? | -- | ||||||||
9 | Probe the 5 volt reference A circuit with a test lamp connected to B+. Does the test lamp illuminate? | -- | ||||||||
10 |
Does the test lamp illuminate? | -- | ||||||||
11 |
Did you find and correct the condition? | -- | ||||||||
12 | Locate and correct the short to ground in the EGR valve pintle position circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |||||||
13 |
Did you find and correct the condition? | -- | ||||||||
14 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Important: If the EGR valve shows signs of excessive heat, check the exhaust system
for blockage (possibly a plugged converter) using the procedure found in the
Restricted Exhaust System Check
. If the exhaust
system is restricted, repair the cause; one of which might be an injector
which is open due to one of the following reasons:
Did you complete the replacement? | -- | -- | |||||||
15 |
Did you find and correct the condition? | -- | ||||||||
16 | Locate and repair short to ground in the 5 volt reference A circuit. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | -- | |||||||
17 |
Did you find and correct the condition? | -- | ||||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Did you complete the replacement? | -- | -- | ||||||||
19 |
Does the DTC reset? | -- | System OK |
