If you use your truck for industrial work, farming, or any industry where flammable particles are in the air, engine runaways can happen. An engine runaway happens when your truck ingests flammable particles such as gas and oil vapors and the engine "runs away' using that flammable vapor as fuel. Even tuning the key off will not stop the engine. The only way to stop an engine run away is to cut off the engines air supply otherwise, major engine damage can occur. The PacBrake PH+ PowerHault does just that. This device utilizes the factory throttle valve on your intake manifold to close off the air supply in emergency situations to shut down the engine. Protect your truck and your life with the PH+ Emergency Engine Shutdown System.