So it's been really cold lately, with the car gauge reading -25 Celsius (-13 Farenheit), and just before my last fill-up (Saturday) I had the yellow-check engine light come on. Nothing registered on the car-computer (car info> system check, etc.) and there was no impact on driveability.

Now I left it outside for about 24 hours and drove it to the gym on Monday (~30min drive) and as I shut off the car a low battery warning pops up on the car computer. I park it outside and it started up just fine after my workout - I drive it to work and decide to park it underground. At the end of the day, it starts up fine and there's no low-battery indicator when I shut it off. The check engine light also disappeared when I started it up today (opened and closed the gas cap - and it cleared after a bit of driving), and no warning lights showed up today.

Looking through the forums - it sounds like the usual suspect for the yellow light - is the gas cap. So I'm thinking this could all be chalked up to the cold weather:

• low gas in the tank= more air, with the cold temp. causing a decrease in pressure = yellow check engine
• electrolyte losing its effectiveness at cold temp. = low battery reading

but wanted to see if anybody else in the deep-freeze has experienced anything similar? I'll definitely bring up the battery-warning at my next-service, because if this less than one year old battery is having problems withstanding the cold - I wouldn't want to see what a 2 or 3 year old battery would do in the cold...

 

Agreed, I would chalk it up to the cold weather...

The Battery electrolyte can freeze if the temps drop low and long enough that can make the car unhappy (make any car unhappy)

And your assumption about the fuel tank air density fuel cap seal sounds plausible as well... ever notice that some times after a week of driving when you break the seal of you fuel cap there is the sound of air equalizing? With the lower temps that internal pressure can change as well...

Additionally in some extreme cases the vent/return line can freeze closed and as the fuel pump removes fuel the blocked line causes the fuel tank to collapse (a sign of this is noticing the fuel gauge reading higher than you remember it was earlier in the week or more fuel indicated than your mileage driven represents)

Motor on!

 

Respectfully I'd have to disagree with at least two of these assertions.

To the best of my knowledge a fully charged battery is not in danger of freezing. Certainly a discharged battery can freeze (and crack the case), but if your battery was discharged enough to freeze then this is the result of a problem elsewhere.

The test that sets the MIL if the fuel cap is loose involves putting a slight vacuum on the fuel tank and timing its bleed down to ascertain the entire fuel system is vapor tight. The pcm follows very restrictive rules on the conditions under which this test can be performed - ambient temp, fuel level between 1/4 and 3/4, engine operating conditions, etc. Any initial pressure/vacuum would have no affect on this test.

And a fuel tank collapsing from vacuum due to a clogged vent? I guess it could happen, but it surely doesn't sound likely or benign.

 

It hasn't been that cold in Chicago (though damn near close). I have no real answers for your battery question but I am wondering if you leave the Start/Stop function active during the extreme cold?

While I'm under the assumption that BMW engineers took extreme cold into account when designing Start/Stop, the skeptical old man inside of me has decided to turn off Start/Stop during the winter just to put less load on the battery and to make sure it's fully-charged before I turn it off for an extended period. My decision could be completely unfounded by science but hey, it's worth a shot.

Matt

 

Even if the check engine light has gone out, a qualified MINI technician can scan the car and tell you what the fault was for. It's probably worth it to find out. I assume your car is still under warranty...

 

Start/stop permanently off in my car ; i found it too unsettling to have the engine kick in at a stop light, I bet BMWs I-6 engines are smoother - but that 3 cylinder is just a little too rough at start-up for me to keep start/stop on.

But yes - the battery puzzles me; the engine light I'm pretty confident was the pressure dropping due to temps and I was driving pretty hard on a low tank just prior to the light coming on.

The battery didn't give me any problems on start-up, it was just a warning at the end of my drive; even though one of my drives was ~30 mins , more than enough time to fully charge the battery. I would compare it to a cellphone dying in extreme cold, but when warmed to room temperature would have a sufficient charge to operate normally. Yes the chemicals are different - cellphone vs. car battery, but concepts should carry-over - with the electrolyte loosing effectiveness when outside of its normal operating range.

anways, no problems since and today was -20 celsius (-4 F); so I'll just monitor for now. Thanks for all the feedback, stay warm!

 

Check engine light and low battery message at the end of my drive to work today, it's -26C this morning. This is my 3rd check engine light, the first apparently the car thought it had a low battery, they cleared that one, the 2nd is a #3 injector leak, still waiting on the part to fix that (but I'm cleared to drive the car while we're waiting), and now this is the 3rd time I've seen it. I'm not sure what I think of this battery!

 

i got a message on my 2015 mcs today that says baterry discharging while stopped but no check engine light.

 

it was very cold that day and was doing some datalogging on jb4 no problems since!

 

A couple months ago I got the battery discharge warning. I'm in NC so certainly wasn't cold related. It was a bit alarming, but I never had any trouble starting the car. The warning went away as mysteriously as it appeared and has not come back.

 

"Battery discharging while stopped",
came on in my 2014 F56S. 6900 mi.
Dealer Diagnosis... re program, replace battery.
Cause ???
We live in So. Cal. and it has been 85 degrees F. here.
Waiting for a new battery.
See complete post under " "Battery being drained while stopped"