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.
Conditions for Running the DTC
| • | The Ignition 1 Signal parameter is between 11-18 volts. |
| • | The EGR valve is commanded to open. |
Conditions for Setting the DTC
| • | The difference between the EGR Position Sensor parameter and the Desired EGR Position parameter is more than 8 percent. |
| • | The above condition is met for more than 10 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: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||
2 | Is DTC P0403 or P0405 also set? | -- | Go to Step 3 | |||||||
3 |
Does the EGR Position Sensor parameter remain within 8 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 9 | ||||||
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 13 | Go to Step 11 | ||||||
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 10 | Go to Step 12 | ||||||
9 | 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 17 | Go to Step 14 | ||||||
10 | 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 17 | Go to Step 14 | ||||||
11 | Test the EGR valve position signal circuit for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
12 |
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||
13 | Test for an intermittent and for a poor connection at the EGR valve. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 15 | ||||||
14 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Repairing Connector Terminals in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 | ||||||
15 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
16 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||
17 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 18 | ||||||
18 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
