V40 Low Brake Fluid

Hey, I have a V40 too, and I had something similar happen. Low brake fluid can be a sign your brake pads are wearing down. As the pads wear, the pistons in the calipers have to extend further, which uses more fluid from the reservoir, making the level drop. Have you checked your pads lately?

That's interesting. I didn't realize the pads could cause that. How would worn pads affect the brake fluid level exactly?

Basically, the system for hydraulic brakes is sealed. As your brake pads wear down from pressing the pedal, the pistons have to move more to compensate. So the space the piston occupies in the caliper cylinder has to be filled with fluid. If it gets too low, the warning light will turn on and you'll have very spongy brakes. I'd get it checked out by a professional ASAP.

Thanks for the advice! I took it to a shop, and you were right – worn brakes. Got them replaced, along with a fluid replacement and it cost 480€. Everything's back to normal now.