I doubt that there is an OBD code for this, ha ha ha, but Larry Carley of Enginebuilder magazine on at least 2 occasions has stated in articles, that the above will allow "unmetered" air into the intake port. The quotes are his. I assume he meant the air intake port and thus the combustion chamber. He goes on to say that this creates an effect similar to (worn throttle shafts or a vacuum leak in the intake manifold). Either the above is the stupidest statement in automotive history or I don't know anything about air flow in the engine compartment. Valve guide seals are designed to let a small amount of oil leak past the guide seal so as to lubricate the upper end of the valve stem. Oil is not air. Even if there is improper seating of the air intake valve itself along with a loss of compression the air doesn't come from anywhere except the air intake manifold. All the air that gets into the oil sump and the upper head area and that flows out the PCV valve (or if you have a vacuum pump that gets sucked out that way) originally got there via the air intake manifold and past the mass air flow sensor which meters the air. Except for a head gasket leak , a leaky EGR valve, or the 4 systems that use vacuum such as (power break booster system, the EVAP system, PCV hose or the HVAC system); how unmetered air would get in any engine compartment if there is no leak in the air intake manifold I would like to ask Santa Claus.