The EGR valve works by recirculating exhaust gases back into the combustion chamber. This produces hotter gases, which allows the engine to burn more cleanly and efficiently. From constant use and hot air flow, EGR valves accumulate carbon and unburned soot on the inside of the diaphragm. They can clog completely, shutting off the hot gas flow. EGR valve failures can cause engine symptoms like stumbling, cylinder misfires and rough idling. If your vehicle requires a scheduled smog test, non-working EGR valves can cause the vehicle to fail the emission control test, requiring a repair-replacement and a followup smog check. The vehicle owner can sometimes clean the EGR valve by spraying carburetor cleaner inside the unit. For those persons who do not wish to gamble and buy a new replacement EGR valve, removing the old unit can be accomplished with few basic hand tools.
Place the car in park or neutral with the emergency brake on. Raise the hood. Remove the negative battery terminal. Make sure the engine is cool--the EGR valve sustains heat, and injury can result by handling the part with bare hands.
Locate the EGR valve. It looks like a small diaphragm, with vacuum hoses connected to the top of it. The valve unit will be bolted to the intake manifold. Gently move aside any wires or other hoses, so you have free access to the EGR valve unit.
Disconnect the vacuum hoses from the top of the EGR valve body, by pulling them free, or loosening the clamp that holds them in place (if so equipped). Be sure to mark the hoses in the exact order they were removed. Wedge them aside away from the valve.
Remove the clamp that holds the hot air supply hose to the bottom of the EGR valve body. The clamp will be either a spring-type or a hose-type clamp. Use the slot screwdriver for the hose clamp, or a pair of pliers for the metal spring variety. Gently twist the hot air supply hose from side to side, while pulling in a downward direction. Do not force it--the hose can be brittle from heat exposure, and can break easily. Prop the hose away from the EGR valve.
Spray the EGR valve mounting bolts with solvent spray and let soak for a few minutes. Remove the bolts, using the appropriate size metric socket or hand wrench. Make note of the bolt locations and place them aside.
Use a gasket scraper to clean the EGR mounting surface on the manifold, then wipe with a solvent rag. The mating surface between the valve and intake manifold should be clean and free of debris.
