Erratic camshaft position due to low oil pressure
Oil flow restriction in the oil passages or the variable camshaft timing (VCT) valve body
Camshaft advance mechanism binding (VCT unit)
Damaged VCT phaser
Radio frequency interference (RFI)
Engine Light ON (or Service Engine Soon Warning Light)
The Powertrain Control Module (PCM) monitors and evaluates the response of the actual position on a target position change. The setpoint and camshaft position are saved at the beginning of a setpoint change. If this change over time is large enough (gradient), the camshaft phasing change is evaluated. If the change after the diagnostic time is smaller than a threshold, a slow response is detected, and if the value is greater, then there is no concern. By detecting a concern, an antibounce counter is incremented otherwise the counter is decremented. If the counter exceeds an adjustable limit, the P000B is set.