High beam (main beam) indicator
The high-beam (main-beam) headlamps are on. UN R121 makes the tell-tale blue; FMVSS 101 allows blue or green, and blue may be blue-green (note 4). Blue is the only dashboard colour the colour code reserves for one lamp.
BlueGreen
What to do
Dip to low beam when you meet or follow other traffic, so as not to dazzle other drivers.
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
- Headlamp with straight, level beams
- Colour
- Blue or Green
What the colour means
Blue — “main beam only”
The colour code says “Blue shall be reserved exclusively for the main beam headlamp tell-tales” (Directive 2009/80/EC, Annex I, 2.1.4). UN R121 item 3 makes the high-beam tell-tale blue; FMVSS 101 allows blue or green, and blue-green (note 4).
Green — “safety”
The colour code gives “green: safety” (Directive 2009/80/EC, Annex I, 2.1.4). In both tables green marks lamps that are simply switched on — turn signals, dipped beam, position lamps — and FMVSS 101 also allows it for the high-beam telltale.
Where the regulations list it
| Rule | Row | Colour it sets |
|---|---|---|
| FMVSS 101 | Table 1, “Highbeam” — telltale | blue or green |
| UN R121 | Table, item 3 “Headlamp high beams” — tell-tale | blue |
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
- Both rules allow four or five beam lines (UN R121 note 13, FMVSS 101 note 5).
Other green 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.