Circuit Description
The exhaust gas recirculation (EGR) valve position sensor is monitored by the powertrain control module (PCM). The 5-volt reference circuit, low reference circuit and the EGR valve position signal circuit are used by the PCM to determine the EGR valve position. The PCM compares the EGR Position Sensor parameter with the desired EGR Position parameter when the valve is commanded open or closed. If the PCM detects a calibrated difference between the EGR Position Sensor parameter and desired EGR Position parameter for a calibrated amount of time, DTC P0404 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0404 Exhaust Gas Recirculation (EGR) Open Position Performance
Conditions for Running the DTC
| • | DTC P0641 and P0651 are not set. |
| • | The engine is running. |
| • | The Ignition 1 Signal parameter is more than 11 volts. |
| • | The Desired EGR Position parameter is more than 0 percent. |
| • | The EGR valve is not being commanded with a scan tool. |
| • | The DTC P0401 intrusive test is not active. |
| • | The change in the EGR Position Sensor parameter is less than 30 percent for 1 second. |
| • | The EGR command will be disabled if the start-up ECT is less than 5°C (41°F) and will not enable until the ECT Sensor parameter is more than 75°C (167°F). |
| • | DTC P0404 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The difference between the EGR Position Sensor parameter and the Desired EGR Position parameter is more than 10 percent for longer than 100 seconds.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Inspect for excessive deposits on the EGR pintle or seat. Inspect for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick. |
| • | If the condition is intermittent, refer to Intermittent Conditions . |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||||||
2 | Is DTC P0403, P0405, or P0406 also set? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 | ||||||||
3 |
Does the EGR Position Sensor parameter remain within 15 percent of the desired EGR Position parameter when commanded with a scan tool? | -- | Go to Step 4 | Go to Step 5 | ||||||||
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||||
5 |
Observe the EGR Position Sensor parameter with a scan tool. Is the EGR position sensor parameter less than the specified value? | 1% | Go to Step 6 | Go to Step 11 | ||||||||
6 | Connect a test lamp between the 5-volt reference circuit of the EGR valve and the low reference circuit of the EGR valve. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 8 | ||||||||
7 |
Is the EGR Position Sensor parameter more than the specified value? | 99% | Go to Step 9 | Go to Step 13 | ||||||||
8 | Connect a test lamp between the 5-volt reference circuit of the EGR valve and a good ground. Does the test lamp illuminate? | -- | Go to Step 12 | Go to Step 14 | ||||||||
9 |
Important: If the scan tool output control function times out, re-command the EGR valve to 100 percent before the next electrical measurement is taken.
Is the calculated resistance more than the specified value? | 3 ohms | Go to Step 15 | Go to Step 10 | ||||||||
10 |
Important: If the scan tool output control function times out, re-command the EGR valve to 100 percent before the next electrical measurement is taken.
Is the calculated resistance more than the specified value? | 3 ohms | Go to Step 16 | Go to Step 17 | ||||||||
11 | Test the EGR valve position signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
12 | Test the low reference circuit of the EGR valve for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
13 | Test the EGR valve position signal circuit for the following conditions:
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
14 | Test the 5-volt reference circuit of the EGR valve for an open or for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
15 | Test the high control circuit of the EGR valve for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
16 | Test the low control circuit of the EGR valve for resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 18 | ||||||||
17 | Test for an intermittent and for a poor connection at the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 19 | ||||||||
18 | Test for an intermittent and for a poor connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 | ||||||||
19 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
20 | Replace the PCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 21 | -- | ||||||||
21 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 22 | ||||||||
22 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK | ||||||||
