Give it some lawn food to green up the leaves. It's pretty.

That looks exactly like a Bearss lime, and yes they do turn yellow as they ripen.

The ones in the store are picked green as they store and ship better when green. But they're juicier and have a more complex flavor when tree ripened to yellow.

Bearss limes have a milder flavor than Key/Mexican limes, but they're larger. They're also seedless, or nearly so.

Nice tree to have, congrats!

Does look like a bearss. I have a tree and I think the fruit tastes more like a traditional lime when used green with just a tinge of yellow to the skin. If you wait until the skin is yellow all around, the flavor is not as good, in my opinion. However, I love the contrast of the yellow skin to watery green color on the inside so I let some get completely yellow then cut open to use as decoration in drinks.

If it's relatively bland, and not super sour, maybe it's a "sweet lime". I bought some at the international market once, thinking they would be amazing. Actually they were insipid, with diluted palatably tangy limeish flavor.

Citrus limetta

We have a tree like this, and love it. Also in SoCal, SFV area. Someone, I think one of two pro arborists that have consulted here, told us it is a mexican lime although it is clearly not the more common Mexican lime that has smaller green/green fruit. The tree is not too big, maybe 8' and I'll guess it is about 10-15 years old. The fruit on ours starts green, when ripe turns bright yellow and jumps off the tree. We get two or three harvests a year. The fruit, green on the inside, has great texture and flavor, our favorite for limeade or margaritas and I use them in cooking quite a bit. I do not find a taste difference between greenish fruit and fully yellow fruit, except that if picked too soon (when still all green) they are decidedly less ripe and more sour tasting.

There is a Giant Mexican Lime variety, which is a possibility, but I'm still convinced it's a Bearss Lime. A lot of arborists not fully educated on fruit trees, most of their work is done with shade trees, in my experience.