A Camshaft Timing Over-Advanced (Bank 2)
The engine computer has found that the intake camshaft on bank 2 is too far advanced or not moving as expected. This can be caused by dirty oil, a bad oil control valve, a stuck cam phaser, or wiring problems.
The vehicle may still run, but it can idle poorly, lose power, or run rough. Avoid hard driving and get it diagnosed soon because continued driving can worsen engine damage or drivability problems.
P0021 means the engine control module detected that the intake camshaft timing on bank 2 is more advanced than the commanded position, or the system is not responding correctly. This is usually a variable valve timing problem involving oil pressure, the oil control solenoid, cam phaser operation, timing components, or sensor feedback. On some vehicles, the fault can be intermittent and set only under certain engine speeds or oil temperatures.
It is moderately serious. The engine may still run, but performance and reliability can suffer, and the problem can get worse if the oil or timing system issue is ignored.
Yes. Low oil level, dirty oil, or the wrong oil viscosity can prevent the variable valve timing system from working correctly.
Sometimes. If the issue is caused by dirty, old, or incorrect oil, an oil change may solve it. If the solenoid, phaser, or timing parts are failing, more repair is needed.
Bank 2 is the side of the engine that does not contain cylinder number 1. The exact location depends on the engine design.