How to Clean an EGR System
Exhaust gas recirculation (EGR) circuits are subject to carbon build-up. When this happens, a car is likely to have driveability issues. It may jerk, ping or hesitate under a load. It will set check engine codes and a service light will come on. EGR replacement valves are expensive. It is always a good policy to check for carbonization before replacing parts.
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Instructions
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Remove the EGR valve and any supply pipes that may run from the exhaust manifold to the valve. Be certain to work while the engine is cold. Severe burns are possible since the EGR circuit is directly connected to the exhaust manifold. Refer to the manufacturer's instructions for vehicle-specific procedures.
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Clean the EGR valve seat area with a pick to chip out any carbon deposits. If the carbon residue is severe, the valve is likely defective. They are precisely calibrated, must operate in extreme temperatures and are easily damaged. Do not immerse the valve in any solvent.
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Clean the supply pipe. If the valve has an exhaust gas supply pipe, remove it and inspect the inner length. Thoroughly remove any carbon blockage. It can be cleaned with solvent, brushes, picks or any method that effectively removes the carbon. Submerse the pipe overnight in a suitable solvent (e.g., Berryman B-12 Chemtool) if necessary.
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Reassemble the valve and pipe. Use new gaskets. Clear all the stored computer codes. Start the vehicle and check for exhaust leaks. Perform an extensive test-drive and allow the engine to reach operating temperature. Be aware of driveability issues and watch for the check engine light to illuminate.
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Tips & Warnings
Often, an inoperable EGR system or check engine light referring to the EGR system is caused by a defective exhaust manifold, muffler, catalytic converter or rusted exhaust pipes. They all work together and must all be in good shape.
Do not assume an EGR problem is repaired if the check engine light does not immediately illuminate while on a test-drive. EGR circuits often operate just below marginal conditions that will take weeks to meet failure criteria programmed in the vehicle's computer.
