Imperial says it will install replacement parts to deal with vibration detected at Kearl's ore-crusher unit.
It didn't provide an estimate about how much production will be lost during that period or provide a target date for a startup.
Kearl had been producing about 92,000 barrels per day on average through the third quarter, excluding the impact of a 14-day shutdown in September.
It was designed to produce up to 110,000 barrels per day but hasn't reached that level since startup 18 months ago.
The oilsands operation — about 70 kilometres north for Fort McMurray — is a joint venture between Imperial Oil and its parent, Exxon Mobil Corp., which owns a majority of the Canadian company's stock.
Kearl was built at a cost of $12.9 billion — $2 billion over its previous estimate.
The company met legal and regulatory delays in bringing the enormous pieces of South Korean-made equipment to the mine site, which were shipped across the Pacific and then through the United States and Canada by river barge and truck.
The 200 modules had to be broken up into smaller pieces so they could be transported along highways in Idaho and Montana and then put together again near Edmonton.