Thought I would share this because there are so many damn threads about it in the brake section with some correct and some very wrong answers. Do NOT overfill the resoivoir like some people say - the car was not designed to have fluid above the max line. Mine sits nicely inbetween min and max.
90% of the time the reason you are getting that message is because of a dirty brake fluid level sensor (assuming you're not ACTUALLY low on fluid).
The sensor is part of the resovoir cap which is super easy to access. I'm going to tell you how to fix this (unfortunately no photos - camera not good enough). It's very simple to fix, just follow these steps.
1. Disconnect the plug/loom from the brake fluid resoivoir cap. While you're at it, inspect the connection in case that's causing the issue.
2. Twist and remove the cap. You will notice there is a white tube connected to the bottom of it. Close your bonnet and/or cover the resoivoir while you're working on the sensor so nothing flies in.
3. Grab some pliers, gently grip the tube section and twist about half a turn anti-clockwise. You will feel it click, this means you can now pull the whole tube off (first time i did this i thought you kept twisting until it came off, it's definitely a case of twist then pull out). I used my hands to pull it out so it's not that hard.
4. Once removed, you will notice there is either some dirty as hell fluid in the tube, and/or the small wire itself is covered in dirt. You need to spray this with electrical/brake cleaner and then rinse thoroughly. You may even get away with just a rinse. Rinse inside the tube and the wire-sensor part.
5. Allow to air-dry for some time, you don't want any water to be mixed in when you put it back.
6. Push the tube back into the cap, and twist clockwise with your hands until it clicks in place and you can't pull it out.
7. Put cap back on the car, plug the connection in. Boom, you're done.
This is actually VERY easy and i believe ANYONE can do it, even those who are not mechanically minded at all. Instantly fixed the problem for me. If problem persists, then maybe the fluid is low, the loom is faulty, or the sensor is genuinely broken.
Please note: This is different to the generic 'brake system warning', this is only for the seemingly random 'low brake fluid' warning.
Friday, November 27, 2015 - 01:59 am, by: David Grima(Maltezr)
Cheers for posting up this Rory.. Will definitely give this a go as my fluid is at proper level and I only tried cleaning the outside of the tube on the cap.. Which didn't work. My low fluid warning comes on intermittently on my Uzz31 with TRC everytime i drive it