Why does my LEGO® light brick not work?

If the light brick does not work, it is almost always the batteries.

New set: pull the tab out first

A new set has a black tab on the underside. As long as it is in, the LED gets no power.

Old set: the batteries are flat or leaked

The 2x3 light brick has two LR41 button cells, also sold as 192 or AG3. They are fitted at the factory. In a set that spent years in its box they can be flat or have leaked.

• There is one small cross-head screw on the underside.
• Use a well-fitting precision screwdriver with a sturdy handle and press firmly. A tiny watchmaker's screwdriver can strip the screw.
• Put the new cells in the same way round as the old ones.

Does it only light while you press it?

Then it is fine. This light brick only lights while you press it in.

Still dark with new batteries?

LEGO does not sell the LED separately and gives no instructions for it. Handy builders solder in a new LED themselves, watching plus and minus. After that it is no longer an original LEGO® part. A new light brick is the easiest route.

Other light bricks

A Powered Up or Power Functions light has no battery of its own. It is powered by the hub or the battery box. If it does not work, check the batteries there.

Everything about this light brick, including where to buy it and the batteries: light brick 54930c02.