National Highways said the repairs at the A5 Emstrey island were due to be competed overnight last Friday into the morning of Saturday. The lights are now in full working order.
The lights were damaged on December 11, when a car ended up in the middle of the roundabout.
At the time National Highways said the repair work was unlikely to be carried out until the new year due to an issue getting parts.
A spokesperson said before the work was done: "The repairs are due to be carried out overnight 21 and 22 January, between 9pm and 5am.
"Obviously any works may be affected by unforeseen circumstances such as severe weather but assuming all goes to plan this should complete the repairs and the lights be up and running again."