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 P0642

Step	Action	Values	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 - 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. 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 3	Go to Intermittent Conditions
3	Turn OFF the ignition. Disconnect the accelerator pedal position (APP) sensor. Turn ON the ignition, with engine OFF. Measure the voltage from the 5-volt reference circuit of the APP 1 sensor to a good ground with a DMM. Is the voltage within the specified range?	4.7-5.2 V	Go to Step 7	Go to Step 4
4	Observe the DMM while disconnecting all other components connected to the 5-volt reference, one at a time. If voltage changes when one of the above components are disconnected, replace the component. Refer to the appropriate replacement procedure below: Engine Oil Pressure Sensor and/or Switch Replacement Exhaust Gas Recirculation (EGR) Valve Replacement Fuel Rail Pressure (FRP) Sensor Replacement Was a component replaced?	-	Go to Step 8	Go to Step 5
5	Test each 5-volt reference 1 circuit for a short to ground. Refer toCircuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 8	Go to Step 6
6	Replace the ECM. Refer to Engine Control Module (ECM) Replacement . Did you complete the replacement?	-	Go to Step 8	-
7	Replace the APP sensor. Refer to Accelerator Pedal Position (APP) Sensor Replacement . Did you complete the replacement?	-	Go to Step 8	-
8	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 3	Go to Step 9
9	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