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Matsuda conjectured that if $G$ is an $n$-vertex 2-edge-connected graph such that $n \\ge 2a+b+\\frac{a^2-3a}b - 2$, $\\delta(G) \\ge a$, and $\\sigma_2(G) \\ge \\frac{2an}{a+b}$, then $G$ has an even $[a,b]$-factor. In this paper, we provide counterexamples, which are highly connected. Furthermore, we give sharp sufficient conditions for a graph to have an even $[a,b]$-factor. 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An even $[a,b]$-factor of a graph $G$ is a spanning subgraph $H$ such that for every vertex $v \\in V(G)$, $d_H(v)$ is even and $a \\le d_H(v) \\le b$. Matsuda conjectured that if $G$ is an $n$-vertex 2-edge-connected graph such that $n \\ge 2a+b+\\frac{a^2-3a}b - 2$, $\\delta(G) \\ge a$, and $\\sigma_2(G) \\ge \\frac{2an}{a+b}$, then $G$ has an even $[a,b]$-factor. In this paper, we provide counterexamples, which are highly connected. Furthermore, we give sharp sufficient conditions for a graph to have an even $[a,b]$-factor. 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