The risks of driving a vehicle with a Control Valve problem can be severe and should not be taken lightly. When a Control Valve is malfunctioning, it can cause a decrease in fuel efficiency, power loss, engine stalling, and difficulty starting the engine. In some cases, the valve can become blocked and lead to a dangerous build-up of fuel pressure. This can cause the engine to backfire, or even worse, malfunction and catch fire. Therefore, it is important for a Volkswagen car owner with a Control Valve problem to take their vehicle to a trained and certified technician for inspection and repairs as soon as possible.