Valve Simulators: When valves are eliminated, the ECU stores what is known as a ‘soft code’ in the system, which may not appear on the dash. While this code is not harmful, who wants it? Enter the AWE Electronic Valve Simulators. These simple devices plug right into the factory harness in place of the exhaust valves and prevent any code from ever being stored in the ECU due to the removal of the exhaust valves. Plug them in. Start it up. Drive away. That simple. Comes as a set of two.