In this episode of Bumper to Bumper, Dave and John break down the most common—and most misunderstood—diagnostic trouble code in modern vehicles: EVAP system faults. From gross leaks and small leaks to why replacing the gas cap often doesn’t fix the problem, we explain how evaporative emissions systems actually work, why these codes get ignored, and what drivers (and DIYers) should know before clearing that light.

If you’ve ever been told “it’s just an emissions thing,” this episode is for you.