Well I fitted a GFB DV+ valve to my car today in preparation for a remap and it seems to throw an error code after a few miles. I've stripped it off and refitted it four times, made sure I've followed the instructions properly, and each time after a few miles the service light comes on. Weirdly, if I scan for codes, there isn't anything logged and clearing them clears the light, but after a few more miles it comes back on again. I've fitted the stock one back on for now as I'm driving up to Scotland next week and don't want to have to faff about with it.