How Do I Know If My BMW 335i VANOS Solenoid Is Bad?

For your BMW 335i engine to function properly, the position of the intake and exhaust camshafts need to be controlled. The VANOS system is tasked with the job of adjusting engine timing by changing the position of camshafts with respect to the drive gear. By doing so, it makes the engine a more sustainable source of power.

VANOS system was developed by BMW in 1992 and based on the configuration it is of the three different types: single VANOS, double VANOS, and double VANOS with Valvetronic. To adjust the position of intake and exhaust camshafts, the VANOS system essentially controls the oil pressure within the system. And, to regulate the oil pressure it employs a set of solenoids.

VANOS solenoid failure due to daily wear and tear can result in several performance issues and can even cause irreparable damage to the engine. This article will go into detail on the way VANOS works and what would happen in the event of VANOS solenoid failure.

What does the VANOS system do?

VANOS or Variable Nockenwellen Steuerung (in German) or Variable Camshaft Timing essentially adjusts the position of intake and exhaust camshafts by the following means;

• Sensors located in the engine bay monitor the camshaft position and inform the engine control unit about it.
• The control unit then computes the engine speed and data received from the aforementioned sensors and issues commands to the VANOS solenoid accordingly.
• The solenoid then regulates oil pressure within the VANOS piston in an attempt to adjust the intake and exhaust camshaft position so that engine can operate smoothly in all driving conditions.

Now that we know the working of VANOS solenoids in overall engine operation, let's discuss how to tell if they begin to fail.

What are the symptoms of a bad VANOS solenoid?

Rough engine idle

A common finding in a BMW 335i with a bad VANOS solenoid is rough engine idle. It happens due to a defective VANOS solenoid that fails to adjust the camshaft position in relation to the engine speed. Ignoring this problem can result in engine failure. Therefore, make sure that you are diagnosing and fixing this issue on time.

Low engine power

Declining engine performance in your BMW 335i can indicate many serious issues- including a defective VANOS solenoid. The VANOS system is supposed to work in such a way that the engine performance can be enhanced. However, a malfunctioning VANOS system with a defective solenoid won't be able to do its job in a proper way; which may result in a significant loss of torque and power.

Increased fuel consumption

If your BMW 335i engine is consuming more gas than usual, something within the VANOS system is probably at fault. The VANOS system adjusts the camshaft position so that the engine can run in a very efficient way. If the system fails to do its job due to a broken solenoid, your car engine would run rough and burn more gas than usual.

Check engine light is on

Another most common symptom associated with a failing VANOS solenoid is the illumination of the check engine light. A defective VANOS system can adversely affect your BMW 335i engine operation. When the onboard diagnostic system finds out about the irregular engine performance, it would set off the check engine light in an attempt to alert the driver. You can use a computer scanner to retrieve the error code.

Car struggles to cold start

If you are finding it hard to wake up your BMW 335i, then this is definitely a sign that the VANOS solenoid is defective or there is a problem somewhere in the VANOS system that needs to be taken care of.

How to test your BMW 335i VANOS Solenoid?

If you’re suspecting that your VANOS solenoid is failing, get it tested by a certified mechanic before it leads to bigger problems. To perform the test everything you need is a multimeter. And, if you’re getting inappropriate multimeter readings, the VANOS solenoid is defective and needs to be replaced.

In conclusion

The VANOS solenoid is a vital part of your BMW 335i engine. Without a properly functioning VANOS system, your car engine might not perform at its full pace. And, if you don't address the issue on time, it may cause serious damage to your car engine. Therefore, if you're noticing any of the above-listed signs, get your VANOS solenoid tested right away.

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