what's causing my car to throw this code? ever since i cahnged my tall valve covers it's been throwing this code. everything seems to be pluged in correctly.
running tall valve covers with breather on oil cap neck,ls6 valley cover. also running LT's so no cats. any help would be apreciated. thanks.

 

anyone? i checked for a vacume leak spray carb cleaner on the manifold sides and nothing.