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Variable valve timing systems have been around since the 1960s in one form or another, but they didn’t start seeing widespread use until the 1990s, when the DOHC system became prominent. They’ve advanced a lot since then, and today, most automakers have their own proprietary variable valve timing system. The variable valve timing switch is a pressure switch, and is designed to be open on a normal basis. It’s located at the VVT solenoid inside the engine and is responsible for telling the car’s computer if oil pressure was delivered to the VVT system. After pressure has been delivered, the switch closes, creating a voltage drop to 0. The car’s computer interprets this as a positive signal of oil pressure delivery. If the variable valve timing switch fails or reads incorrectly, it can cause the engine to run rough and fuel economy will be affected. The Check Engine light will come on with variable valve timing codes.
The variable valve timing switch is an internal part, and cannot be checked visually. Aside from regular maintenance during the process of oil changes, there are no preventative measures you can take against VVT switch failure. If your car’s Check Engine light is on and associated VVT symptoms are present, have one of our expert mechanics diagnose and repair the problem.
With a faulty variable valve timing pressure switch, your VVT system cannot operate correctly or may not operate at all. This will have a significant impact on overall engine performance, and can lead to serious damage. We recommend having your engine inspected immediately for any suspected VVT switch related problems and repaired as soon as possible.