Linear exhaust gas recirculation valves use a computer-controlled motor to open and close the valve instead of the traditional vacuum method. Linear EGR valves open and close based on the amount of exhaust the engine control module determines the engine needs at any given time. The linear EGR is an electronic component, so in order to test the valve you will need a multimeter to measure the voltage.
Turn the engine off. Open the bonnet of the vehicle to access the EGR valve. The EGR is found mounted on the intake manifold or directly next to it. The position will vary by manufacturer; check your repair manual for a detailed diagram. Locate the wire harness on the top of the valve.
Set the multimeter to the "Volts DC" setting. Clip the red multimeter lead a wire-piercing probe. Push the probe into the third wire on the harness. The harness will consist of five wires; the third wire is the middle wire coming from either side. Clip the black multimeter lead to a ground point, such as the vehicle negative battery terminal.
Turn the ignition key to the "On" position. Do not crank the engine. The "On" position signals the Powertrain Control Module to begin sending signals to various sensors, including the linear EGR.
Monitor the multimeter; acceptable range for a good linear EGR is between .6 and .9 volts DC. If the multimeter reads above .9 volts DC the valve may need to be cleaned or replaced. If the multimeter reads zero or below .6 volts DC then the valve is faulty and should be replaced.