The exhaust gas recirculation (EGR) valve on an LS1 engine is mounted on the passenger-side exhaust manifold and has a small pipe that travels up to the front of the intake manifold, just behind the throttle body. This valve is part of the emission control system, and helps to reduce harmful tailpipe emissions. A failing EGR valve will cause excessive nitrogen oxides to accumulate in the exhaust gas, causing the "service engine" light to appear and the vehicle to fail an emissions test. Replacement EGR valves are available from auto parts stores and licensed General Motors dealerships.
Place the vehicle's transmission into park or first gear (manual). Turn off the engine and engage the emergency brake. Open the hood and disconnect the negative battery lead using an 8-mm box-end wrench.
Disconnect the EGR valve's electrical connector. Remove the two 10-mm bolts holding the EGR pipe to the exhaust manifold using a 3/8-inch ratchet, ratchet extension and a 10-mm socket.
Remove the two 10-mm bolts holding the EGR pipe to the intake manifold using a 3/8-inch ratchet and a 10-mm socket.
Remove the two 15-mm bolts holding the EGR bracket to the engine using a 3/8-inch ratchet and 15-mm socket.
Remove the EGR valve and its pipe assembly from the engine as one unit.
