Let circle have center at \((a, b)\) and radius \(r\). Since it passes through origin:
\[
a^2 + b^2 = r^2
\]
And intercept on line \(x = 2\) is 4 units \Rightarrow vertical length of chord = 4
Use perpendicular distance from center to line = \(\sqrt{r^2 - d^2}\) or compute using geometry. Final equation: \(y^2 + 4x = 8\)