How to Test a Diverter Valve

The diverter valve helps the turbo boost in your car.

The diverter valve in your vehicle, otherwise known as the blowout valve, provides a pathway for boost when it isn't in use by the engine. In other words, the valve provides a way out for the boost during times of shifting or deceleration, when the boost has nowhere to go. When the diverter valve is not working properly, the boost can move back into the engine and cause the turbo to lag or damage to occur in the vehicle.

Things You'll Need

• 1/4-inch drive 6-point 8-millimeter socket

Instructions

1. Make sure that the engine is off and then locate your vehicle's diverter valve. The diverter valve is located on the side of the turbo booster near the throttle. It is a round-shaped valve with a hose connecting it to the throttle.

2. Disconnect the diverter valve from vacuum hose by pulling gently. Insert the drive socket into the valve to compress the valve spring. Use caution to avoid damaging the valve diaphragm.

3. Close the vacuum connection (where you removed the vacuum hose) with your thumb. Remove the socket from the other end of the valve.

4. Feel the suction. If the valve is damaged, it will lose suction quickly. This means you need to replace it. If suction remains consistent, the valve does not need to be replaced.

References

• Euro Sport Accessories: Diverter Valves
• VAG Links: How to Test a Bosch Diverter Valve DIY