2025 BMW M850i xDrive Variable Valve Timing Control Solenoid Replacement Cost

The check engine light, and loss of power are the most typical symptoms of the variable valve timing control solenoid failure. There may be a leak around the solenoid, but this generally will not cause failure. When the solenoid fails, the driver feels a loss of power because the timing is no longer advancing with engine speed. The less fortunate form of failure is from the solenoid advancing at all times. This will lead the engine speed rising and falling at idle, vibrations at idle, and possible misfires at idle. In any case of a failed variable valve timing solenoid, there will be poor fuel mileage until the issue is corrected, because the engine can no longer adjust for maximum economy while cruising.

As most vehicles before variable valve timing, the vehicle may be driven without repairing the variable valve timing control solenoid. The engine performance symptoms noted will be present until the repair is completed, but the engine should not suffer failure due to loss of variable valve timing. If the variable valve timing control solenoid has failed, and causes the timing to remain advanced, the vehicle may have difficulty starting, or not start at all. In these cases, the solenoid should be replaced before the vehicle is operated.

Variable valve timing components fail randomly. There is no great way to recommend when they fail, because replacement occurs for nearly all variable valve timing solenoids across a wide range of mileages. The solenoids are not designed to fail, they typically fail because of dirty oil, or oil that has broken down, and is not as thick as it once was. Regular maintenance according to the manufacturer specification for driving conditions will help ensure the variable valve timing control solenoid is preserved.

So many of these solenoids look alike, regardless of make and model. However, they are built to different specifications, and in most cases are not interchangeable. Using the part number written on the old solenoid, or obtaining the part number using the vehicle identification number (VIN) is the best way to ensure the proper part is purchased the first time.

Second hand solenoids and solenoids from unknown vendors are typically not reliable. There are many solenoids that are built to fit the vehicle, but very few of those are built to the original manufacturer's standard. The aftermarket responded to the cost of these solenoids, and began producing copies as cheaply as possible, and sell them, without branding, through many online retailers. Again, if the vendor is unknown, it is probably not built to OEM standards.

Replacing the variable valve timing control solenoid switch is very easy on most models, and only requires removing the solenoid and moving one electrical connector. If unsure of the sensor location, or if you are unable to diagnose the vehicle, have a professional technician service the variable valve timing solenoid.