That seems a bit soon. The EGR (Exhaust Gas Recirculation) Valve's job is to introduce exhaust gas into the intake air stream during low/no load conditions (cruise) where power demand is at a minimum to help cool the cylinders. This cylinder cooling lowers emissions (NOx mostly) and the exhaust gas doesn't burn again. So in theory you will build up carbon in doing so, but 13,000 miles seems way too soon. Unless you're running excessively rich. This explains the plugs, but the smell would be so bad there'd be no mistaking it.


Justin