Emergency services were called to State Highway 1 just north of Hampden at 2.30pm and the uninjured driver was taken to Oamaru Hospital as a precaution.
Acting Sergeant Graeme McPherson, of Oamaru, said the fire engine was the only vehicle involved in the crash.
SH1 was reduced to one lane while the crash was investigated.
Police had yet to determine what caused the crash.
Fire Service assistant area commander (East Otago) Trevor Tilyard said the engine was a spare Dunedin-based appliance sent to Oamaru as cover for appliances sent to Christchurch.
The extent of the damage was unknown, he said.
He confirmed the driver was a Dunedin firefighter who was returning from Christchurch, and what caused the accident was unknown.
