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08-31-2025LAST POST
Hi guys,

For the first time since i own my M3 i had a check engine light that came on last sunday night. It was damn cold here in ottawa, canada (-35F).

Car was running rough and i have scanned the code on the next morning and it was U1118 !! From my research its something between the signal from a computer to the other or something like this. Can it also be something else???

It was fine all day monday and last night i went and start the car after work and the damn code went on again, and yes it was still the U1118.

Im looking to see if some of you guys have experience this before and what was the outcome???

Thanks
Mike
Are you on the original factory battery still? It might be time to swap. Try charing it with a trickle charger before you replace it, though. It's hard to diagnose electrical gremlins :( Sorry I can't be of more help.
-35°F that's "-37° Celsius" ... Holy 5H1T !
Mike ,your balls must freezing off out there...So personal I think your battery has a hard time to keep up !
So as stated above just connect a good battery tender and let it sit overnight ...
Amirsm3 wrote
Are you on the original factory battery still? It might be time to swap. Try charing it with a trickle charger before you replace it, though. It's hard to diagnose electrical gremlins :( Sorry I can't be of more help.
Yes car is still under the original battery !! Car has 70k so ill see if i still have the same issue when temperature gets a little warmer !! Thanks for the help :)
///M Power-Belgium wrote
-35°F that's "-37° Celsius" ... Holy 5H1T !
Mike ,your balls must freezing off out there...So personal I think your battery has a hard time to keep up !
So as stated above just connect a good battery tender and let it sit overnight ...
Yes its a damn rough winter this year for us !! It was -40c past saturday night !!! Both previous owners of the car had heated garage so i guess its something new for my baby to deal with cold temperature like this haha
An ///M without a garage? I'm surprised BMW hasn't come and taken it back! Good luck with your issues and (attempt to) stay warm.
Code U1118 came back on about 3 times since ive made this post... car always starts fine do i really need to buy another battery?
MikeeM3 wrote
Code U1118 came back on about 3 times since ive made this post... car always starts fine do i really need to buy another battery?
i'ts just a battery, change it before it leaves you stranded somewhere.
Patrón wrote
i'ts just a battery, change it before it leaves you stranded somewhere.
+1

My E90 (323i, my winter beater) had some issues due to extreme cold. Rear window defroster & heater stopped working due to weak battery. Is battery covered under warranty?
MikeeM3 wrote  
Code U1118 came back on about 3 times since ive made this post... car always starts fine do i really need to buy another battery?
I'd suggest leaving the car on a battery tender before you decide to shell out the cash to replace it. Also if you take your car to a BMW dealership or a certified BMW garage, you can have them scan your battery to see how it's life and performance is doing. Way better options than replacing the battery if It isn't needed.
buy a battery tender from Canadian Tire. It's about $40, a lot cheaper than a new battery. I live in Alberta where it's constantly -40 throughout the winter which can be 6 months long at a time. I always have my m3 hooked up to Battery tender. No problem yet!
Hello MikeeM3

I also just got on my 2011 M3 coupe E92 check engine light code U1118 and code U1118P it's cold here in Washington DC also

Just want to know if you was able to resolve the error code U1118 on your M3, I read some people say it's a battery replacement, just want know before I spend $400.00 on a new battery.

Thanks
Check Engine code U1118???
I replace the battery 90Ah 900 C Crank, No more error codes on the 2011 BMW M3 coupe, any one that get's the error message just replace the battery
Battery
When I had a BMW motorcycle they recommend that you put it on a battery tender when you're not riding it so the battery charges fully. I've done that will all my cars and I haven't had to replace the battery in any of them, and my M has had the same battery for 5 years. Just keep them charged up whenever possible, it will extend the life of the battery.
I recently changed my battery and right now I have the U1118 Code but car starts up fine is this code not safe to drive it with it? What does it mean and how can I fix it also I have the increased emissions light too