Hate to ask the stupid question, are you sure the cap is tight and the gasket is good? The light doesn't measure position of the cap, its either a pressure or vacuum sensor. So there is the off chance if its been on that long, you could still have a problem.


99 XJ Sport 2 Door, 4.0L, 5 speed, all stock. Daily Driver
79 F150 Standard Cab Short Box, 400ci, NP435, NP205, 35" SSRs