Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. 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 4 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.
P0420 or P0430 Catalyst System Low Efficiency Bank 1 or 2
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) Connector End Views or Engine Controls 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 | Are any other DTCs set? | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | Go to Step 3 |
| 3 | Inspect for the following conditions:
Did you find and correct the condition? |
Go to Step 5 | Go to Step 4 |
| 4 |
IMPORTANT:
Before replacing the 3-way catalytic converter (TWC), correct any conditions that may have damaged the converter. Replace the catalytic converter. Refer to Catalytic Converter Replacement
in Engine Exhaust.Did you complete the replacement? |
Go to Step 5 | - |
| 5 |
|
Go to Step 2 | Go to Step 6 |
| 6 | 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 |