Hello, I ask my question first: Does anyone know what is wrong with the car when the CEL keeps coming on? Now the background: I purchased this car about 3.5 months ago with a bit over 16K miles on it. The car is fully loaded (except cold weather package). I love the twin turbo diesel engine, the quick takeoff, the over 400 pounds of power, and all the bells and whistles. The production date is 12/2009. After driving the car for about a month, the DEF warning light came on. I took it to the local BMW dealer and was told when the original dealer performed the first service apparently they never topped off the DEF - I was told it would cost around $185. I complained that this has nothing to do with me and it is not in any way my fault. I called the BMWNA Customer Service and after going back and forth with them was told that I had to pay this dealer and if I had any complains I had to pursue it with the dealer that performed the original maintenance service. After about a month of driving, the yellow CEL came on. I took the car to the local dealer. They ran some tests, didn't find any problems, cleared the fault, drove the car for eight miles, and the light didn't come on again - I hesitantly picked up the car. Three weeks later, the CEL came on again. I took it back to dealer. This time the tech found that the SCR injector bore was completely clogged with white soot. They remove it, cleaned it, installed it back, drove the car for 30 miles and all was OK. Three weeks later, the CEL light came on. I called for an appointment but when I got into the car to drive it down to the dealer, the light was not on anymore so I canceled the appointment. A week later, the CEL came on again, made another appointment, took the car to the dealer and now it has been with them for a few days, they can't find the fault, the SA told me they have called BMW engineers and are now waiting for resolution.
Maybe somebody will have more Maybe somebody will have more specific insight. Offering up remote armchair diagnosis of the check-engine light isn't all that simple, as there are any variety of factors, or combination thereof, that can trigger the CEL, but it's possible somebody around here has seen a similar problem to yours and will have worked through it. Over the years, it's been quite common for any new BMW model &/or engine to have issues evolve that weren't able to be exposed or discovered in the development phase, and those may be addressed in different ways by BMW through the production run of the model. Technical bulletins, service advisories, production changes, etc. With the twin-turbo diesel still being a relative newcomer, you may find yourself in the midst of just such a thing, either some quirk that's unique to your car, or a more commonly-found issue (or, perhaps, eventually more-commonly found... it's possible to be among the first to experience a problem, so it's a mystery now, but becomes widespread enough later to be a common problem). Diagnosis of issues tied into the electronics, particularly with how inter-related the various car systems have become, is an ever increasing problem, as each new model and engine introduces an increasing level of complexity, meaning it gets more difficult to solve problems like what you're experiencing. The computer says one thing, the techs fix that but it doesn't resolve the issue for good, and you're back to a mystery. I know that doesn't offer much insight to solving your specific issue, but I imagine if you saw a flow-chart showing everything that's tied into what can trigger a CEL, you'd get a headache.. well, maybe you're an engineer and it wouldn't, but.. I'd get a headache! In the meantime, good idea to keep asking questions, and if it gets solved, share the solution for others. Hope they figure it out for ya!
Two things about this 1st thing is: filling the DEF tank is part of the FREE maintenance, for the first 48K/5 years. Doesn't matter which dealer you go to, free is free and they should have just filled it up. 2nd thing is that (if you look around on different forums), almost the only problems the diesels are having related to SES lights is failure of the SCR injector, or crystalization of the DEF in the lines, tank or injector, or a failure of the pumps in the DEF tank. Most likely you're stuck with a tech and SA at the dealership that can't replace the injector until BMWNA approves it. Hang in there.
