Proudly installed your shiny new blow-off valve without as much as a cheeky sideways-glance at the instructions, but somehow it’s not working properly? Had your race-car-mechanic uncle expertly fit it for you but still ain’t gettin’ that BOV whoosh? Forum gurus offering you pearls of wisdom like: “Errr, what’d you fit a BOV for?”, “GFB BOVs are #*@%, get a brand X that’ll fix it!” or “Everyone knows you can’t vent-to-atmosphere on a [insert your car]”?

Don’t worry; GFB will have you sorted in no time. But before you ask us, take a good look at this troubleshooting guide; in almost all cases we’ll only give you one of the answers that you’ll find below anyway. Blow-off valves really are incredibly simple devices and there are very few things that can go wrong with them, so this guide should be all that you need.

Almost 100% of ‘faulty’ blow-off valves reported to us turn out to be installed or adjusted incorrectly, and can be rectified very easily; we’ve almost never found a problem with any of the valves that have been returned. The troubleshooting guide below lists the eight most common BOV problem scenarios and how to fix them. Go on; show your uncle how it’s done.