My brake system light came on yesterday. Car is garaged at night - garage usually around 50 degrees in the winter. Temps in my area all day yesterday between -2 and 9 degrees. Car was in an unheated, frigid parking structure yesterday from 8 am to 5:30 pm. Remote started from my office desk at 5:25 pm, made way out to the car, (interior already pretty comfy after about 5 minutes), fully started, backed out of my space, braked, and noticed the brakes felt very soft and un-grabby, enough to make me go "whoa, uh oh!" to myself. Noticed brake system light was on. Wasn't surprised given the "whoa, uh oh" moment. Pumped the brakes a few times, light stayed on. Drove forward a few feet, braked, same soft feeling and need to really shove hard on the pedal to make the brakes grab. The parking brake light also came on, indicating that it automatically didn't disengage. Visions of having to have the car towed or flatbedded to the nearest dealership dancing in my head, I tried shutting the car down and restarting. Presto. Warning light for brake system came on briefly as it always does, then went out. Put in drive, pressed the accelerator gently and the parking brake disengaged normally. Very carefully drove forward and tested the brakes again - felt normal. Did my normal 35 minute drive home and everything felt fine. This morning started up and drove in to the office normally, no weird brake feel and no warning light. Car is in the frigid garage again today, it is expected to be a bit less cold today out.

Should I worry?

 

Has your brake fluid ever been maintained? Sounds like you may need a brake fluid flush because brake fluid is hygroscopic and absorbs water, the water in the lines may be freezing.

 

Yes, as part of regular service intervals. I am going to make an appointment - this is something I do NOT want to mess with. Thanks!

 

Update: Dealer tech checked the brake system and everything seemed fine. Thinks the extreme cold on the day was to blame. Since restarting the car caused the problem to go (and stay) away, he thinks there was a glitch somewhere in the sensor. He also checked the brake pads and said they are still almost like new.