[lknbimmers]

Noticed the yellow Service Info light come on last nite as I was heading home. When I checked for the message, the idiot light displayed was Low Brake Fluid.

Can I really be low on brake fluid? Only have 15k miles on the clock and the brake pad life is showing 20k miles till replacement. My rule of thumb is to never top off the brake fluid.
Has anyone else encountered this issue?

[BimmerPod]

bump - i have the same issue. Never heard of having to "top off" brake fluid. Any common causes?

[kevin@bavarianx]

Check the reservoir if it is low then top it off. Should not be that big of a deal because brake fluid can boil off.

[ENINTY]

I don't think the brake fluid has "boiled off". It's a sealed system.

Considering you drive in heavy NYC traffic it's probably quite normal to use up pads pretty quickly. The CBS system only estimates pad life and doesn't really measure it, and it may not be giving you an accurate estimate of pad life. The formulas BMW uses to estimate the pad life may not properly account for NYC traffic. So as pads wear down additional fluid is needed to bring the fluid level back up to full because the pads are thinner and the piston inside the caliper sits farther out of the cylinder bore, which leaves more volume in the caliper cylinder to be filled by brake fluid. As the pads near their minimum thickness limit it would be possible for the system to need additional brake fluid if all four brakes are near their limit for replacement. Your car has brake force distribution, which proportions the hydraulic pressure somewhat evenly amongst the four brakes, so it is quite normal for all four brakes to need replacement at nearly the same time.

I'd top off the fluid with DOT 4 brake fluid (the dealer will do it for free under the maintenance program) and not worry about it. The only other reason for the fluid to be low is a leak, which would show up immediately with a change in pedal feel and braking performance. Your car is too new for rusted lines, so it would only be either a caliper piston seal went bad, or a fitting in the lines at the master cylinder or brake caliper was not assembled correctly at the factory and has now become loose to the point that it is leaking. Or possibly a bleeder valve was not properly tightened during manufacture and is now leaking. Look for wet spots on the brake calipers for evidence of a leak.

[F32Fleet]

Are you sure it's not stating you need a brake fluid change? When/How long ago was your last fluid change?

[jlE90]

are u sure u use dot4? my fluid cap says something like cf11 only (i thought the dam brake fluid is a dealer item)

[RFGuy_KCCO]

Originally Posted by jlE90

are u sure u use dot4? my fluid cap says something like cf11 only (i thought the dam brake fluid is a dealer item)

You are looking at the power steering fluid cap, not the brake fluid reservoir cap.

[ENINTY]

Originally Posted by jlE90

are u sure u use dot4? my fluid cap says something like cf11 only (i thought the dam brake fluid is a dealer item)

Are you sure you are looking in the right place? The brake fluid reservoir is under a plastic cover on the cowling in front of the windshield next to where the hood strut attaches to the body. If you are looking at the black round reservoir in the engine bay, that is the powersteering fluid.