The 'drain water from diesel fuel filter' light came on last weekend. Like you say, the picture in the owner's manual looks clear enough. But I've been under the car, under the bonnet and under the engine cover and I can't find it! Got the wife to take it to Fisken's in Forfar. An hour later they said there's no water in the filter, but the sensor's been sheared right off! How? Where? Never been off road! Just potholes and puddles, like everyone else. Awaiting Vauxhall's advice. Oddly, warning light goes out, occasionally! Does anyone know where the fuel filter and sensor are?