PCV Breather Filter - help What's a PVC Breather Filter and do I need to replace it? PCV Breather Filter: The PCV breather filter assures only clean, filtered air is drawn in through the PCV breather. A clogged breather filter prevents the PCV from siphoning away the blowby gases and moisture created by engine combustion, resulting in oil breakdown and sludge buildup. The PCV breather filter should be replaced every 30,000 miles; however, yearly replacements are a good preventive measure. |