Brake system warning light
A fault or condition in the brake system. This is the general brake warning: both FMVSS 101 (note 9) and UN R121 (note 9) say that when one telltale reports more than one brake condition, this is the symbol or word it must use — so on many cars the same lamp also covers low brake fluid and an applied parking brake.
Red
What to do
First check that the parking brake is fully released. If the light stays on, or comes on while you are moving, treat it as a brake fault: slow down gently, stop where you can do so safely, and read the owner's manual before going further. If the pedal feels soft or travels further than usual, have the car checked before using it again.
Makes differ: what this light means on your car, the other colours it may use for the symbol and what the car wants you to do are set by the manufacturer, so your car's owner's manual is the authority.
- Symbol
- Circle with ! between two arcs
- Colour
- Red
What the colour means
Red — “danger”
The colour code that UN R121 points to (ISO 2575, paragraph 5) is sold, not published. The EU wrote it into law for two- and three-wheel vehicles in Directive 2009/80/EC, Annex I, 2.1.4: “red: danger”. FMVSS 101 does not define colour meanings, but S5.5.6(b) says a telltale for which red is required must not be cancelable while its underlying condition exists, and note 4 to Table 1 allows red to be red-orange.
Where the regulations list it
| Rule | Row | Colour it sets |
|---|---|---|
| FMVSS 101 | Table 1, “Brake system malfunction” — telltale, word “Brake” | red |
| UN R121 | Table, item 25 “Brake system malfunction” — tell-tale | see UN Regulations 13-H and 13 |
FMVSS 101: Passenger cars, multipurpose passenger vehicles, trucks and buses sold in the US (S3). Table 1 gives the symbol or words and, where one is required, the colour of each telltale; Table 2 lists identifiers with no colour requirement. UN R121: Cars (category M) and light goods vehicles (N1) type-approved under the UN 1958 Agreement, which includes the EU, UK and Japan (para 1). Its table gives the symbol and colour of each tell-tale; note 2 says the symbols are substantially identical to those of ISO 2575:2004.
Good to know
- US cars may show the word BRAKE instead of the symbol: FMVSS 101 Table 1 identifies this telltale by the word “Brake” and requires it to be red.
- UN R121 does not set the colour itself; its column 5 says “See Regulation Nos 13-H and 13”, the brake regulations.
Other red lights
Sources
- eCFR — 49 CFR 571.101, Standard No. 101; Controls and displays (current text) — checked 2026-09-23
- govinfo — 49 CFR 571.101 in the Code of Federal Regulations, 1 October 2025 edition (Tables 1 and 2 as printed) — checked 2026-09-23
- EUR-Lex — UN Regulation No. 121 (01 series), Official Journal of the EU L 5, 8 January 2016: table 'Symbols, their illumination and colours' — checked 2026-09-23
- Directive 2009/80/EC, Annex I, point 2.1.4 — the tell-tale colour meanings as written into EU law (for two- and three-wheel vehicles) — checked 2026-09-23
Meanings are written in our own words from these public texts, not quoted from ISO 2575, and were checked on the date shown.