Part of what makes BMWs so great is their use of advanced technology to enhance performance and driving enjoyment. However, this also comes with the need to repair and/or troubleshoot this technology when things go wrong. The VANOS system in BMWs is a good example of this.
VANOS is a German acronym for VAriable NOckenwellenSteuerung, which in English essentially refers to variable valve timing. Although plenty of vehicles have variable valve timing, VANOS is a system unique to BMW.
In variable valve timing, engine performance is improved by controlling the timing of the valves. In a double VANOS system, this is the intake and exhaust valves, whereas in single VANOS systems, only the intake valve is involved. This is accomplished by moving the camshaft in relation to whatever the drive gear is at the moment.
In simpler terms, the intake and exhaust is more precisely controlled, leading to a more efficient, smoother, and more powerful engine with better MPG, smoother idles, and greater torque and horsepower.
Unfortunately, the VANOS system is not perfect, and does need maintenance or even replacement. Let’s go over some of the symptoms of a bad or failing VANOS solenoid, which is a type of electromagnet, and talk about guidelines for repair or replacement.
Signs of Failing VANOS System in BMW
- Reduced horsepower and/or torque: The VANOS system, as described above, improves performance, especially torque. So when failing or faulty, performance will drop off. You might or might not notice minor reductions, but any reduction in normal performance is a cause for concern.
- Hesitation and/or bogging of the engine: The engine might struggle to get going when you push the accelerator or even bog down while you are pressing the throttle, leading to dismal performance and a significant reduction in driveability.
- Rough idle: The engine will run rougher than usual. This can include a change in the way it sounds, as well. Always be aware of new sounds in your BMW as they can signal a problem.
- Reduced fuel economy: The MPG of your BMW might drop. If you notice you are fueling up more or can check the actual MPG via a dashboard feature, the VANOS system might be the culprit.
- Problems with cold starts or even stalling in cold weather: A cold start is the first start of the day, when the engine is completely cool. When VANOS is not working right, it might be even harder to start the car for the first time each day. The engine also might become more sensitive to cold weather such that it stalls! This can be a dangerous situation depending on when and where your BMW stalls.
- Check-engine light: Often, when VANOS is failing, the check-engine light will illuminate on your dashboard. Automotive service centers will be able to use a scanner to extract and read the code for you. However, these codes are general in nature and often more inspection is warranted in order to accurately identify the problem. Do not ignore check engine codes as they can signal severe trouble and without maintenance, can lead to further or greater damage and even more costly repair bills.
- Limp mode engaged upon acceleration: Limp mode can be described as a protective mode for a vehicle. It drastically reduces power and overall performance in order to protect itself by limiting further damage to the engine.
Although many of these symptoms can be caused by things other than failing VANOS solenoids, the system should still be suspected as it is known to wear out over time. For example, the solenoids themselves sometimes become dirty or clogged in addition to just failing. The seals of these solenoids are often fairly worn by the time your BMW reaches 50,000 miles and are likely to be in need of a repair or replacement by the time you hit 70,000 miles. Given how severe symptoms are, replacing or even just cleaning the solenoids to prevent complete failure is advised.
Corpus Auto Service for BMW VANOS Service
Family-owned and operated for over 35 years, Corpus Auto Service in Corpus Christi, Texas is the prime location for your BMW’s needs. We also serve customers in nearby Portland, Rockport, Aransas Pass, and Calallen TX.
At Corpus Auto Service, you’re treated like family. Let our ASE certified technicians using state of the art equipment help you get your BMW taken care of and back on the road with a 1-year warranty on all repairs to give you peace of mind. To schedule an appointment, call us at 361-855-6421. We can be found at 2732 S. Padre Island Dr. Corpus Christi, TX 78415.
* BMW Car image credit goes to: andreonegin.