BMW E65 Valvetronic faults (N62)
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E65 N62 warning light and power limitation appear as the engine warms up - what can cause it?
The cause can be an internal fault in the Valvetronic control box, shown as fault code 285E. Code 2865 is merely a consequence of the power limitation, not a separate fault. After the control box is replaced, the car's software must be updated.
Can the fault be in the cylinder head adjusting motor instead of the control box?
Yes. Sometimes the control box is fine and the cylinder head adjusting motor is only partly broken. The adjusting motors can be swapped from one side to the other: if the fault moves with it, the fault is in the motor.
How do I know the fault is not in the Valvetronic but in the mass air flow sensor?
Uneven running and a warning light at about 1500 rpm can be caused by the mass air flow sensor, even if the Valvetronic adjustments seem to have failed. The fault codes then point to the air mass meter and the intake air temperature. Check the sensor before expensive Valvetronic parts.