The federal government is investigating 5,000 school buses from the 2008 model year that could stall without warning.
There have been no accidents or injuries reported. But in at least three cases, high-pressure oil lines that connect the oil pump to the fuel injectors allegedly failed on International CE-brand buses.
The National Highway Traffic Safety Administration posted a notice about the investigation on its website Sunday.
In one case reported to NHTSA, a bus full of students was going 55 miles per hour when it started smoking and stalled. The driver pulled the bus to the side of the road.
International CE buses are made by Lisle, Ill.-based Navistar Inc. The company says it will cooperate fully with the investigation.
Government investigations sometimes lead to vehicle recalls.