Brake fluid is essential for your braking system to work properly. Checking it takes just a few minutes and can help you spot potential safety issues early.
Your car parked on level ground
A cold engine (recommended, but not essential for brake fluid)
A torch (optional, helps see the level clearly)
Open the bonnet.
Look at the rear of the engine bay, usually on the driver’s side.
Find a small translucent plastic reservoir mounted on top of the brake master cylinder.
It is usually labelled “Brake Fluid” and has a warning symbol.
The reservoir will have MIN and MAX markings on the side.
Without opening the cap, visually inspect the fluid level.
Interpretation:
Between MIN and MAX: Normal
Below MIN: Low brake fluid → needs attention
Near or at MIN: May indicate worn brake pads or a possible leak
Low brake fluid can happen due to:
Worn brake pads (most common cause)
Fluid leak in the braking system (more serious)
Evaporation over time (rare in modern systems)
If it’s low, don’t just top it up without checking why.
If the level is low:
Check your owner’s manual for the correct DOT specification (e.g., DOT 4 is common in many UK cars)
Clean around the reservoir cap before opening it (prevents dirt entering the system)
Slowly add brake fluid up to the MAX line
Do not overfill
Tighten the cap firmly.
Wipe away any spills immediately (brake fluid damages paintwork).
Close the bonnet securely.
Check brake fluid about every 3–6 months.
If the level drops noticeably between checks, get the braking system inspected.
If the brake warning light appears on the dashboard, check fluid immediately and have the system inspected.
Never drive with a brake warning light on without investigating.
Brake fluid is highly corrosive to paint—clean spills quickly with water.
If braking feels soft, spongy, or less responsive, seek professional inspection immediately.