The Woking squad ran its Honda-engined MP4-29H development car in the final test of 2014 in Abu Dhabi last month, but the car completed just three full laps across two days as it suffered a spate of electrical problems.
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Boullier said after the test that the car would be returned to Woking for a "full investigation" and did not rule out using another 'filming day' before 2015 testing commences to make up for lost time.
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Speaking to reporters at a special media conference called to announce McLaren's 2015 driver line-up on Thursday, Boullier said work to fix the electrical problems was ongoing.
"They worked hard for a week, found out everything, and a recovery plan is in place," he said.
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"It was not only one problem. There were hardware issues that made the wrong software codes, so we had to first find out what was wrong in the hardware system to fix the software system.
"Part of it has already been fixed, there are now some further tests on dynos to validate."
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