Temporary traffic lights have been erected at a busy Ribble Valley junction while county council engineers work to fix the main traffic signals.
A spokesman for Lancashire County Council warned drivers of possible delays on Accrington Road near Whalley while the set of traffic lights are repaired.
The traffic lights are not working due to a cable fault on the set of signals at the junction of the A671 Accrington Road, the main road between Whalley and Padiham, and the B6246 Accrington Road which connects Whalley to the main road.
The traffic lights are currently switched off and temporary lights have been put in place until the repairs are completed.
Daniel Herbert, highways group manager for Lancashire County Council, said: "We're sorry for the inconvenience to people's journeys due to the fault which has developed on these traffic lights.
"We estimate that it will take at least a week to replace the faulty cables and will let people know more once we have investigated further.
"This is a very busy junction, and we'd advise people to find alternative routes if they can until the problem is fixed as delays will be unavoidable."