The easiest way to clear the codes is to disconnect the battery BUT make sure you have your radio code to reset your radio. I had the same problem with the 123 code and found I had the wrong coolant temp sensor I have a 1990 740 turbo I took the old one out and replaced it with one I knew was working. Come to find out that the one that goes in this year and model has a black plastic plug I put a blue one in and got the same message 123 so I bought a new black one and code gone. Ya learn something new every time, try it it works not all temp sensors are the same if it was black put the same one back and so on. good luck. If anyone needs rust free parts at a reasonable price mail me back at ufarley@earthlink.net Cal. Chuck