Police in the North have said the device found in Dungiven last night was viable and had the potential to injure or kill.
It was found by firefighters when they turned out to deal with two wheelie bins on fire at a house at Ard Na Smoll.
It is the third viable device found in the Dungiven area of Derry in the past four weeks.
The PSNI have said it is potentially linked to the other two devices.