Nicholas Latifi lost valuable practice time in Baku on Friday when his car stopped out on track after completing just five laps of FP2 for the Azerbaijan Grand Prix, triggering a red flag.
The Williams driver explained later that the problem was a result of the power unit's protection software designed to ensure that the PU doesn't suffer damage, which had been trigged by an unusual incident.
"I moved out of the way of another car but couldn't turn back left to get back onto the track," Latifi said.
"In the time it took me to reverse from the escape road the power unit got too hot; the safety measures put in place to make sure it doesn't get damage kicked in and it shut off.
"Unfortunately that was the end of my session," he sighed. "You don't want to miss track time, especially on a street circuit, so it's not ideal but we will make the best of it and see what we can do.
Williams head of vehicle performance Dave Robson gave further details of the cause behind Latifi's early end to the day.
"We lost valuable time on Nicholas’s car this afternoon when the power unit protection strategy was triggered following a trip down the escape road.
"Unfortunately, Nicholas couldn’t get the car back on track quick enough to prevent the power unit getting too hot and so the protection strategy intervened to prevent any damage to the unit."
While it was a less eventful day for Latifi's team mate George Russell, the Briton could only manage 17th place in the final standings and was almost two and a half second off the pace set by Red Bull's Sergio Perez.
"George had a smoother day but struggled a bit for pace at both low and high fuel," said Robson. "The tyres are given a hard time on this long track, especially when the track is hot and there will probably be little room for error during qualifying tomorrow."
"It was a tough day here in Baku," acknowledged Russell. "Our competitors are looking a little faster than we expected, but I think with some hard work tonight and the right changes to the set-up we can find some lap time
"I wasn’t pushing the boundaries massively as it’s only practice, so it’s about getting the laps under my belt and finding a rhythm.
"Hopefully I can make it count when it matters tomorrow - Q2 is the goal for me," he added. "I think it’s possible if we can put absolutely everything together."
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