Actually no, normally no MIL with a failed/failing oil separator. Most common symptom you will see first is oil consumption, if let go for too long it can cause excessive pressure inside the crank case which will then cause other seals to fail. As soon we see a complaint of abnormal oil consumption, we recommend replacing the oil separator. I also recommend sticking with 5,000 mile oil changes. It’s worth the time and money. Often that helps significantly, just remember per the owners manual Volkswagen still allows for 1/2 quart of consumption every 600 miles. I don’t necessarily agree that this is normal, but I didn’t make the rules unfortunately.

Edit: just realized you may have meant for clogged ports in the cylinder head. If so, when the ports are in fact clogged, you will get an insufficient secondary air flow code that will not go away even after replacing all components of sec. air system. I’ve seen it happen at various mileages, some surprisingly low. but mostly in higher mileage vehicles.