Winterbottom was weaving at slow speed to put heat in his tyres, directly in front of rookie driver Sam Walter's Commodore during Saturday practice.
Walter was forced to take evasive action, ploughing his car into a wall and doing extensive damage.
Stewards hit Winterbottom with a $A15,000 fine in total - $A10,000 of which was suspended pending any further incident.
It is the third time this weekend Winterbottom has been involved in similar controversy, with Holden rivals Rick Kelly and Garth Tander also believing they were blocked by his car as they attempted to do quick laps on Thursday and Friday.
It is unclear whether Walter's Greg Murphy Racing Holden will be fixed in time for Sunday's 1000km race.
Holden Racing Team's Will Davison topped Saturday morning practice ahead of Ford-driving brother Alex and Holden's Jason Richards.
Three-time world superbike champion Troy Bayliss' difficult Bathurst initiation continued with his Commodore catching fire in the pits.
