Diagnostic Aids

Use the Freeze Frame/Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data may help in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also help in determining the number of ignition cycles that the diagnostic test reported a pass and/or fail. Operate the vehicle within the same Freeze Frame conditions, including those for RPM, for engine load, for vehicle speed, for temperature, and for others. This will isolate at what point the DTC failed.
Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Check if DTC P0461 is also set. Both these codes will set simultaneously if the vehicle was refueled with the engine ON.

DTC P2066 (5.7L)

Step	Action	Yes	No
Schematic Reference: Instrument Cluster Schematics Connector End View Reference: Powertrain Control Module (PCM) 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	Remove the fuel level sender. Inspect for the following items: The fuel level sensor is stuck, perhaps due to an interference with the fuel strainer. The fuel tank contains foreign material, for instance, ice. Did you find and correct the condition?	Go to Step 4	Go to Step 3
3	Replace the secondary fuel tank module. Refer to Fuel Tank Module Replacement - Secondary in Engine Controls - 5.7L. Did you complete the replacement?	Go to Step 4	-
4	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK