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Steve, BMW Expert
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I have 3 issues on my 2006 BMW 750 Li (e66) with 100 000 Km

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I have 3 issues on my 2006 BMW 750 Li (e66) with 100 000 Km (60 000 mi) on it:

About every 2 months, I have a "low coolant" warning, usually when I start in the morning. Usually, about there is about 1/8 or 1/10 gallon missing. I haven't noticed any leaks, not on my driveway, at least. Where should I check for coolant leaks? I haven't noticed any white smoke coming from the exhaust.

I am not sure if this could be related to the previous problem, but it sometimes idles quite roughly when starting (in the morning only). On the worst morning, it feels like there is some misfire. This morning, it did it and I listened to the tailpipe and did hear what seems to be misfire, but just for a few minutes. On 2 occasions, I had to turn off the engine, the start it again and it went away...

This one started when, for absolutely no reason, whenever I started the car, all the windows came down and the sliding roof opened. They wouldn't close for a few minutes (using door switch). When I did get them closed, they would all open again when I pushed the start button to turn off the engine. Again, I had to wait 2 to 10 minutes to finally get them to stay closed with the engine off. ABOUT THE SAME TIME, MY DRIVER DOOR WOULDN'T SHUT (just bounce), but the mechanical latch seemed OK, I could close it with a pen with the door open. It seems like the car did not know the door was closed and wouldn't close the latch. Since then, when I leave the car for more than about 1 hour, the keyless entry stops working (I use the remote) and the radio needs to reload all the CD's from the CD changer (I can hear it) and forgets which one it was playing. I THOUGHT THAT MAYBE THERE IS A PROBLEM WITH THE DOOR SWITCH THAT LOWERS THE WINDOWS OR THE DOOR HANDLE ITSELF AND THE CAR SHUTS DOWN POWER BECAUSE IT CREATES A POWER LEAK ????

OK, that's it, all my problems!


Hi Martin, welcome to justanswer. The coolant leak will need to be ferretted out using a pressure test, small leaks are difficult to find, especially when no coolant is visible on the ground. The rough idle sounds like a problem with a temp sensor or perhaps a vacuum leak. For the door and windows acting up, you will need to have the car scanned to determine exactly what has failed. There are a number of modules on this car that can fail. The one thing you can try though is a battery reset. With the car off, keys out, windows down and doors unlocked and trunk open, unhook the battery for 1 hour. This can sometimes clear out random electrical/computer faults, and is a bit like rebooting a frozen computer. Please let me know if you have further questions. If satisfied with my assistance, please press accept so that I am compensated for my time, effort and expertise. I am not compensated until you press accept. None of the deposit you have paid will be transferred until you press accept.


Customer: replied 7 years ago.
Hi Steve, I read horor stories regarding a coolant leak from a tube, located between the cylinder banks if I recall correctly, the often fails and I was wondering if it's on the 4.4l engine only or also a possibility on mine (4.8l). The reason I am asking is because my warranty will end in 15 000 Km (about 3-4 months for me)... ROUGH IDLE: Would my mechanic get a fault code if it's a temp sensor? Can I get it using the car's computer with the trip reset button ? DOOR HANDLE/ELECTRICAL PROBLEM: Thanks, XXXXX XXXXX try exactly what you said right away. I will disconect the negative cable from the battery in the trunk. OF COURSE, I WILL ACCEPT ANSWER. I will also adjust the amount if it seems unreasonable! Thanks.
Can I please have the last 7 digits of your vin to look a little further into this?
Customer: replied 7 years ago.
VIN: DT38740 (just noticed that door assist stops helping me close the door too after about 1 hour)...

thanks please give me a few min


Customer: replied 7 years ago.

The coolant leak does not appear to affect your engine. If you are under warranty, this should be covered so long as the cause is is not road damage.


A temp sensor would not necessarily set a fault. They will only set a fault if the value reported is unplausible, so they can report an incorrect value, and as long as it is reasonable, it won't set a fault code.


Good luck with the battery reset. Be sure you have the keys out of the ignition, doors unlocked, windows down, trunk open so that you don't get locked out.


Please let me know if you need anything further. Please press ACCEPT if satisfied.





Customer: replied 7 years ago.
Hi Steve,
I just did what you told me (disconnect battery for 1 hour), everything is back to normal. I will see if the problem went away in a few hours when I go back to the car.

Two last question: Are small coolant leaks like the one I have current ? I am going on vacation with the car next week, I will do about 6000 km (4000 mi). If you were me, would you get this done before I leave or it's probably fine to do it when I get back ?

I'm clicking Accept answer after that.


Hi again. It does sound like you do have a small coolant leak, and it may only leak when the car is in operation, this is why I suggested the pressure test to find it. If it were my car. I would have the leak fixed before going on the trip. It simply isn't worth the risk. Please let me know if you require anything further. Please press accept if satisfied. Cheers. Steve
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