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 P0401

Step	Action	Yes	No
Schematic Reference: Engine Controls Component Views
1	Did you perform the Diagnostic System Check - Engine Controls?	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Observe the Freeze Frame/Failure records for this DTC. Turn OFF the ignition for 30 seconds. IMPORTANT: Attaching the shop exhaust system to the vehicle may cause false exhaust gas recirculation (EGR) DTCs to set. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle?	Go to Step 3	Go to Intermittent Conditions
3	Is DTC P0101 also set?	Go to Step 8	Go to Step 4
4	Is DTC P0404 or P1404 also set?	Go to DTC P0404 or DTC P1404	Go to Step 5
5	Is DTC P0403, P0405, or P0406 also set?	Go to DTC P0403 or DTC P0405 or DTC P0406	Go to Step 6
6	Inspect for engine vacuum leaks. Did you find and correct the condition?	Go to Step 9	Go to Step 7
7	Inspect the exhaust system for leaks, for restrictions, and for a modification of the original equipment manufacture (OEM) parts. Did you find and correct the condition?	Go to Step 9	Go to Step 8
8	Remove the exhaust gas recirculation (EGR) valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement . Inspect for the following conditions: A stuck open EGR valve Leaks in the EGR valve and EGR passages Restrictions in the EGR valve and EGR passages. Debris or damage that can cause the EGR valve to stick partially open or partially closed-Refer to Exhaust Gas Recirculation (EGR) System Cleaning . If the EGR valve is sticking or damaged and can not be cleaned, replace the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement Did you complete the repair?	Go to Step 9	-
9	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	Go to Step 2	Go to Step 10
10	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