From day one of purchasing oven B47CR32N0B/93 four years ago it frequently warns it needs cleaning despite the fact the oven is spotlessly clean. According to a NEFF engineer this is because the oven registers too many cooked roast meals. ABSOLUTE RUBBISH!! We are a two person family with below average oven usage (we have two Neff ovens - the other is a steam oven, which has not required a deep clean since it was purchased at the same time). At the time of purchasing the ovens we also purchased three other Neff appliances, and all appliances were manufactured in 3 different countries! I recently contacted customer services to explain the oven saga but the operator was only interested in selling a costly visit by an engineer, who would undoubtedly repeat what the other engineers have said!! ABSOLUTELY NO HELP WHATSOEVER! It is my view that the oven in question is faulty. Very wary of purchasing Neff in the future!