Birth Code and 2-4-8 Triad

By "birth code" I assume you are referring to the birth date, specifically the day of birth. My assumption is based on your birth day's single-digit value being the number 2.

In Pythagorean numerology (which I use), the birth day number is a core number. The energy represented by the birth day number resonates as a perspective, with how opportunities and challenges are viewed and approached, and with the strongest abilities and talents. The link will provide more information

I've had no experience with a 2, 4, and 8 triad and am unable to say what it might be or represent.

Generally, number-represented triads have an equal distance between numbers. With this one, however, the distance between the last two numbers is double the distance between the first two. A triangle to represent that triad I think would be scalene.