Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- 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.
DTC P0406
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Schematic Reference: Engine Control Module (ECM) Connector End Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Engine Controls? | - | Go to Step 2 | Go to Diagnostic System Check - Engine Controls |
| 2 |
|
4.75 V | Go to Step 4 | Go to Step 3 |
| 3 |
|
- | Go to Step 4 | Go to Intermittent Conditions |
| 4 | Test for shorted terminals and poor connections at the exhaust gas recirculation (EGR) valve. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 12 | Go to Step 5 |
| 5 |
|
0 V | Go to Step 8 | Go to Step 6 |
| 6 | Measure the voltage between the 5-volt reference circuit of the EGR valve and the low reference circuit of the EGR valve with a DMM. Is the voltage less than the specified value? |
5 V | Go to Step 7 | Go to Step 10 |
| 7 | Repair the open in the low reference circuit of the EGR valve. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 12 | Go to Step 9 |
| 8 | Repair the short to voltage in the signal circuit of the EGR valve. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you complete the repair? |
- | Go to Step 12 | Go to Step 9 |
| 9 | Test for shorted terminals and poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 12 | Go to Step 11 |
| 10 | Replace the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement
. Did you complete the replacement? |
- | Go to Step 12 | - |
| 11 | Replace the ECM. Refer to Engine Control Module (ECM) Replacement
. Did you complete the replacement? |
- | Go to Step 12 | - |
| 12 |
|
- | Go to Step 2 | Go to Step 13 |
| 13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List | System OK |