The lights at the Thames-Coquet-Severn Sts intersection, where the Boer War monument is located, were installed as part of a $3.2 million upgrade of State Highway 1 through Oamaru and were switched on in March.
Last month, they were taken out when a truck slid on ice and hit the signal control box. That was repaired.
Last weekend, they went on the blink - the amber light flashing - due to a systems fault. They were fixed again on Monday.
However, on Thursday, they started blinking again and continued yesterday. Signs were put out warning motorists the lights were not functioning.
They were working again late yesterday morning.
The New Zealand Transport Agency (NZTA) is endeavouring to find the cause of the intermittent fault.
Projects team manager Simon Underwood said yesterday the NZTA was looking into the problem.
"Traffic signal engineers are at present working to find what is causing these issues," he said.
While the inconvenience to pedestrians and traffic was disappointing, the NZTA was confident the "initial operational issues" would be resolved.
Experience from traffic signal operations in Dunedin and other centres showed traffic light issues did occur from time to time, but were relatively rare, he said.
The Oamaru system had an automated process to alert the contractor to issues with the lights and, in most cases, the causes.
Work was planned at the intersection next week to repair damage to the traffic lights caused by the July crash, Mr Underwood said.
Prior to the lights being installed, the intersection had the worst crash record in the Waitaki district.
