Identifying Lamp DOT & SAE Markings

What it is

FMVSS 108 sets the US requirements for vehicle lamps and reflectors. Makers mark lenses with "DOT" to show they certify that the lamp meets FMVSS 108. Many also mark one or more SAE function codes from SAE J759, the lighting identification code, often followed by a two-digit year.

A lamp that does more than one job carries more than one code, such as a combination stop, tail and turn lamp.

How to read it

1. Find the markings. They are molded into the lens, usually near the edge.
2. Look for "DOT." It shows the maker certifies compliance with FMVSS 108.
3. Read the letter codes after "SAE." Each letter or letter and number is a function.
4. Read the year. A two-digit number after the codes, such as 08, shows the year of the SAE standard the lamp was tested to.
5. Check the color. Codes do not replace color rules. Stop and tail lamps are red. Front turn signals and front clearance lamps are amber. See FMVSS 108 Lamp Color and Placement Chart.

Common SAE J759 codes

Some codes have number suffixes that show a performance grade or use. Check the full SAE J759 list or the lamp maker's data for codes not shown here.

Key points

• A combination lamp such as "SAE AISTP2" covers reflector, turn, stop, tail and marker functions.
• Replace a lamp with one that carries at least the same function codes.
• Lamps for wide vehicles may need different codes than lamps for narrow vehicles.
• Lamps marked for off-road or "not for highway use" do not meet FMVSS 108.

Common mistakes

• Replacing a stop-tail-turn lamp with a tail-only lamp.
• Using an amber lamp where red is required.
• Assuming an LED lamp meets FMVSS 108 because it fits.
• Ignoring a missing reflector function.

Governing standards: FMVSS 108 (49 CFR 571.108, lamps, reflective devices and associated equipment); SAE J759 (lighting identification code).

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.