Circuit Description
The engine control module (ECM) monitors the position of the exhaust gas recirculation (EGR) valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. This voltage varies depending on the position of the EGR valve. The ECM interprets this voltage as the position of the EGR valve. If the ECM detects a difference between the actual EGR position and the commanded EGR position, 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
| • | The ignition is ON, or the engine is operating. |
| • | The DTC runs once an ignition cycle when the above condition is met. |
Conditions for Setting the DTC
The ECM detects a difference between the actual EGR position and the commanded EGR position.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
Due to moisture associated with exhaust systems, the EGR valve may freeze and stick in cold weather at times. After the vehicle is brought into a warm shop for repairs, the valve warms and the condition disappears. By watching the actual EGR and desired EGR positions on a cold vehicle with a scan tool, the fault can be easily verified. Check the Freeze Frame data to determine if the DTC set when the vehicle was cold by viewing the engine coolant temperature (ECT).
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine 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 P0405, P0406, or P1403 also set? | -- | Go to Step 3 | |||||
3 |
Is the voltage less than the specified value? | 0.80 V | Go to Step 4 | Go to Step 6 | ||||
4 |
Is the voltage more than the specified value? | 3.70 V | Go to Step 5 | Go to Step 6 | ||||
5 |
Did the DTC fail this ignition? | -- | Go to Step 6 | Go to Intermittent Conditions | ||||
6 |
Important: Use a Test Lamp that measures between 25-30 ohms for this test. Does the test lamp illuminate? | -- | Go to Step 8 | Go to Step 7 | ||||
7 | Connect a test lamp between the 5-volt reference circuit of the EGR valve position sensor and a good ground. Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 12 | ||||
8 |
Is the parameter less than the specified value? | 0.05 V | Go to Step 9 | Go to Step 11 | ||||
9 |
Is the resistance less than the specified value? | 3 ohms | Go to Step 10 | Go to Step 17 | ||||
10 |
Is the voltage less than the specified value? | 1 V | Go to Step 15 | Go to Step 14 | ||||
11 | Test the signal circuit of the EGR valve position sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 16 | ||||
12 | Test the 5-volt reference circuit of the EGR valve position sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 16 | ||||
13 | Test the low reference circuit of the EGR valve position sensor for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 16 | ||||
14 | Test the control circuit of the EGR valve for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 16 | ||||
15 | Test the EGR valve for the following:
Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 18 | ||||
16 | Test for an intermittent and for a poor connection at the engine control module (ECM). 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 20 | Go to Step 19 | ||||
17 | Repair the high resistance in the ignition 1 voltage circuit of the EGR valve. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 20 | -- | ||||
18 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||
19 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- | ||||
20 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 21 | ||||
21 | Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
