A slightly long post. Please bear with me
I have a 41K mileage car which recently had an incorrect diesel fluid warning with the will not start in 200 miles warning. This car is still under the 4 year full maintenance warranty and all service has been performed at the same dealer where I purchased the car.
I scheduled an appointment and brought in the car for service 50 miles later assuming they would just need to add diesel exhaust fluid. There was also a check engine light on now. 4 days later they tell me that they installed NOx sensors and coded the car twice being unable to fix it the first time. Then they asked if I topped off the coolant which I didn't. Then they tell me that coolant was found in the diesel exhaust reservoir and I was looking at a $10K repair.
They said that a fault occurred 4 miles before I brought the car into the dealership. They said blue coolant was found in the DEF reservoir and someone (read me) definitively and incorrectly added coolant into the diesel exhaust tank sometime within the previous week which caused the fault and that BMW would not cover the repair. The technician showed me some codes but I am not knowledgeable with regard to that. The SA also said there were currently no leaks detected and the lines are too far apart to affect the other.
They also stated that BMW corporate had been questioning why multiple sensor replacements had not fixed my car and that they (the dealer) informed them of "my negligence" and that I would no longer be able to get a warranty repair at another BMW dealer.
This didn't make sense to me. I have a car still under a full maintenance warranty. I did not go to the dealer to buy coolant and pour it into the DEF tank. That's ridiculous and totally illogical. I, like most people, would go to the dealer to get it fixed for free. Also, they are assuming that I would fix the incorrect diesel fluid warning by adding coolant?
I did however report a burning smell from my car at my previous scheduled maintenance around 4500 miles ago. They said they checked for leaks and didn't detect any oil leaks from the engine compartment. I'm not sure if that would be relevant. They also did an oil change and replaced the cabin and fuel filters as well as added DEF this previous visit.
At this point I'm considering 3 possibilities:
1. A leak into my exhaust system which they previously failed to detect and diagnose
2. A manufacturer's defect
3. Gross incompetence or negligence (intentional?)
I am planning to file a complaint with the Bureau of Automotive Repair and BMW Corporate.
What are your opinions and advice? Mechanical, legal or otherwise. Thanks so much.