McLaren-Honda's running on the opening day of the second pre-season test has been cut short by an engine issue.
After an encouraging 21 laps to start the day at the Circuit de Catalunya, the MP4-30 remained in the garage for a long spell as the lunch break approached. The team then announced that an issue with the MGU-K required a power unit change, which would prevent the car from getting back out on track on Thursday.
Honda confirmed that a faulty seal on the MGU-K requires a redesign, which would prevent a replacement part being manufactured before Saturday's running.
Jenson Button had been at the wheel of the car on Thursday and was due to drive again on Friday, but McLaren has altered its schedule to see Fernando Alonso in the car on day two and Button driving again on Saturday instead.
The issue follows a frustrating first test for McLaren at Jerez, with just 79 laps possible in total over the first four days.
Click here for the gallery from day one of the second test