Canadian Jacques Villeneuve will lose 10 places on the Australian Grand Prix starting grid after BMW Sauber confirmed his car's engine would be changed for Saturday's qualifying.
The Formula One team suffered failures of their new V8 engines in the first two races in Bahrain and Malaysia, and Polish test driver Robert Kubica had to stop in Friday's opening practice after 13 laps.
They have revised components since then, with Nick Heidfeld having a new engine for Sunday without penalty, but Villeneuve was still running the previous version.
"Our whole focus is on reliability, but the time for development was too short," said team principal Mario Theissen, explaining the problem.
"Over the winter our test engines of identical specification covered the required distances without problem.
"However our investigations into the breakages in units after Bahrain and Malaysia revealed that some components have not met their required production tolerances.
"Our short-term reaction has been to build new engines with hand-selected components that best meet these rigorous requirements," added Theissen in a team statement.
"We have two of these revised engines here. One is already installed in Nick's car and Jacques will get the second in time for qualifying after Saturday's morning practice. As a result, he will lose 10 positions on the grid."
Villeneuve, the 1997 champion with Williams who made a sensational debut in Australia 10 years ago when he started on pole and finished second, scored BMW's first points when he finished seventh in Malaysia.
"The balance of the car is very good and I'm really happy with its speed," said the Canadian.