Williams might have to start the 2011 season without KERS.
With its own KERS company Williams Hybrid Power, the Oxfordshire based team initially developed a flywheel system but instead opted for the more tightly-packaged battery version for its 2011 car FW33.
However, it has been troublesome in recent testing and Rubens Barrichello has now admitted it might not be taken to Melbourne in two weeks.
"We need to decide quickly what we are going to do," he is quoted by the Dutch website f1today.nl.
"I hope we do not conclude that we have to race in Melbourne without KERS, but it is possible," admitted Barrichello.
"It is an uncertain factor for us; one day it gives us no problems and the next day it gives us hundreds of problems."
KERS aside, the 38-year-old said he is happy with the FW33 and is targeting "Q3 and a good number of regular points".