Recalled are 2019 Subaru Crosstrek, Forester and Ascent vehicles with aluminum PCV valves that may separate and allow engine oil into the combustion chambers.
Subaru also says components of the PCV valves may enter the combustion chambers, resulting in vehicles that lose power.
Subaru recalled more than 228,000 Crosstrek and Impreza vehicles in October because the PCV valves could separate. The automaker continued to investigate the problem, and engineers found heating and cooling cycles could cause a gap to form between the steel PCV valve washer and the aluminum PCV valve case.
The automaker also determined other components surrounding the aluminum PCV valve case could press into the case and contribute to the separations.
Drivers may notice changes in the appearance and amount of tailpipe exhaust.
According to Subaru, the problem was solved in production lines when the PCV valve case material was changed from aluminum to steel.
More than 51,000 Subaru vehicles are recalled in the U.S. and more than 5,500 are recalled in Canada.
Subaru dealers will replace the PCV valves and possibly remove the separator covers and oil pans. The short block engines will be replaced if the separated parts are not located.
The recall is expected to begin Jan. 24, 2020, but concerned owners may contact Subaru at 844-373-6614.
Subaru's recall number is WUW-08.