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All newer cars seem to suffer this plague although they should not have required cleaning till 70,000 miles for the first time.
The EGR ports are fairly small passages in the intake manifold through which some exhaust gasses travel. Ash and oil residue cause them to clog up. Newer cars will throw a CEL to indicate that there is a problem. The exhaust gasses reduce the combustion temperature and therby reduce nitrogen oxide pollution and also reduce fuel octane requirements.
Use the search function, read around, and next time you go to a stealership, awe them with your knowledge.
