P0020 Lincoln Code - 'A' Camshaft Position Actuator 'A' Control Circuit/Open Bank 2

The Variable Camshaft Timing (VCT) solenoid valve is an integral part of the VCT system. The solenoid valve controls the flow of engine oil in the VCT actuator assembly. As the Powertrain Control Module (PCM) controls the duty cycle of the solenoid valve, oil pressure/flow advances or retards the cam timing. Duty cycles near 0% or 100% represent the rapid movement of the camshaft. Retaining a fixed camshaft position is accomplished by dithering (oscillating) the solenoid valve duty cycle.
The PCM calculates and determines the desired camshaft position. It continually updates the VCT solenoid duty cycle until the desired position is achieved. A difference between the desired and actual camshaft position represents a position error in the PCM VCT control loop. The PCM disables the VCT and places the camshaft in a default position if a concern is detected. A related Diagnostic Trouble Code (DTC) also sets when the concern is detected.
When the VCT solenoid is energized, engine oil is allowed to flow to the VCT actuator assembly which advances or retards the camshaft timing. One half of the VCT actuator is coupled to the camshaft and the other half is connected to the timing chain. Oil chambers between the 2 halves couple the camshaft to the timing chain. When the flow of oil is shifted from one side of the chamber to the other, the differential change in oil pressure forces the camshaft to rotate in either an advance or retard position depending on the oil flow.
This DTC sets when a low or high voltage on the VCT21 circuit is detected. This DTC sets if the voltage exceeds a calibrated limit for a calibrated amount of time

• Low or Dirty Engine Oil
• Incorrect camshaft timing
• Faulty Variable Camshaft Timing (VCT) Bank 2 Solenoid 1 (VCT21)
• Variable Camshaft Timing Bank 2 Solenoid 1 circuit is open or shorted
• Variable Camshaft Timing Bank 2 Solenoid 1 circuit poor electrical connection