PCV Valve

On Light Duty Emission models (up to 8500 lbs. GVW), check PCV valve every 12,000 miles and replace every 38,000 miles. On Heavy Duty Emission models (over 8500 lbs. GVW), check PCV valve every 12,000 miles and replace it every 24,000 miles. Valve is located on rocker arm cover.