Had an intermittent lambda light issue for a while, bought a cheap ebay code reader which read a code with a dirty maf sensor possibly being the first thing to check(think it was p0172). Sprayed the cleaner on as instructed, left it off the car overnight to dry out properly and 3 weeks have gone now without the lambda light coming on. The car is driving better than she has done for ages and I'm very happy with the result.