What does this dashboard warning light mean?
Find it by its colour, then its shape. 1. Pick the colour the light glows. 2. Match the drawing. Every light here is one that US or UN vehicle regulations define, with the row it comes from.
Tap a colour to see only those lights.
Red — “danger” · 10 lights
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.
Treat a red light as urgent: find out what it means before carrying on, and stop when you can do so without creating a hazard if the manual says so.
Yellow / amber — “caution” · 17 lights
The same colour code (Directive 2009/80/EC, Annex I, 2.1.4) gives “amber: caution”. FMVSS 101 and UN R121 write the colour as “yellow”; it is the colour both tables give to malfunction telltales such as ABS, stability control and low tyre pressure.
A yellow light asks for attention soon: something is outside its normal state or a system reports a fault. Find out which, and have it checked.
Green — “safety” · 6 lights
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.
A green light confirms that something you switched on is working. Nothing is wrong.
Blue — “main beam only” · 1 lights
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).
Blue on the dashboard is the high beam. Dip it for other road users.
How the colours and symbols are set
- Two rulebooks. US Federal Motor Vehicle Safety Standard No. 101, Controls and displays (49 CFR 571.101): 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 Regulation No. 121, location and identification of hand controls, tell-tales and indicators (01 series): 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.
- The colour is part of the rule. FMVSS 101 S5.4.1 says each telltale in Table 1 must be the colour that table gives it; UN R121 para 5.4.1 says the same of its column 5.
- Some symbols may change colour. UN R121 note 18 lets the fuel, oil, coolant, charging and high-beam symbols appear in other colours to convey other meanings, following the colour code of ISO 2575 — which is why a blue thermometer on many cars means “cold”, not a fault.
- Everything lights at start-up. A telltale may light during a bulb check (FMVSS 101 S5.3.1(e)); otherwise it lights only for the condition it reports (S5.3.1(e), UN R121 para 5.3.5).
- Lamps not listed here — lane keeping, adaptive cruise, low washer fluid, service reminders and the like — are the maker's own. Neither rule gives them a symbol, so this page leaves them out; they may be any colour that does not mask a listed one (FMVSS 101 S5.4.2, UN R121 para 5.4.2).
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.
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
The eCFR prints Tables 1 and 2 as images; the govinfo edition is the same text as printed. UN R121 has had supplements since this consolidated text; the rows cited here are the ones in it.