Took ownership of a Z4 2.5si a couple of weeks ago. I love driving this car despite it’s little problems. Anyway ... the car had been stood for some time when I bought it. On the way home the engine manangement light came on and it was a Vanos error. We switched it off using my mates Carly. I can normally tell when it’s going to error as the engine revs peak slightly. Anyway ... it was making the usual Vanos sounds so I had an oil service and had the Vanos cleaned ... light came on again. So I decided to buy two new Vanos units. Fitted them with the help of a good friend and the car was totally transformed ... engine runs smoothly, it picked up quicker etc. All was fine ... reversed off the drive and boom ... the lights back on again with a Vanos error. I know when it’s going to happen as the engine revs slightly. I now have new Vanos bought from BMW so I know it’s not them. Seems to be some kind of electrical fault I think. I can drive for about 50 miles before the light comes on. Anyone got any ideas?? Thanks in advance 