Red Bull's Max Verstappen bounced back from an accident in Free Practice 1 to set the third fastest time of the day in Baku on Friday.
But FP2 ended with concern that his car had an issue with its power unit, and Verstappen was ordered to return the RB14 to pit lane at low speed.
Team principal Christian Horner said after the session that it was most likely a minor issue, and possibly just a faulty sensor. A relieved Verstappen was subsequently able to confirm that this was indeed the case.
"We thought we had an issue, but they found out it was a faulty sensor, so nothing to worry about," he said. "All good."
Verstappen had already shrugged off the incident earlier in the day which saw him broadside the safety barriers at turn 6 just half an hour into the session.
"I lost the rear, spun, and of course hit the wall," he said, still bemused by the exact cause. "It was a bit more windy, but I don't know.
"It was a bit slippery at the start - I couldn't catch the car and hit the wall," he explained. "You just have to feel your way into the track because it was very dusty and slippery, as I found out."
Verstappen had to sit out most of FP1 as a result of the accident. Once the car was returned to pit lane, mechanics worked through lunch to effect repairs. In the end, Verstappen was back out on track just 20 minutes into FP2.
"It was a shame," he sighed. "Luckily it didn't affect us too much in the second practice, so I'm quite happy.
"The mechanics did a great job to repair the car, and in second practice we did most of the programme."
Meanwhile, his team mate Daniel Ricciardo went on to set the fastest time of anyone on Friday. That gave Verstappen hope that the team will be in with a chance of victory in Sunday's Azerbaijan Grand Prix.
"We look quick," he said, while remaining cautious of the qualifying modes often employed by their rivals. "We know that in qualifying they have this power mode, so they will be even closer.
"But on the other hand, we still have a bit as well.
"On short runs I'm still fine-tuning a bit what I lost in first practice," he admitted. "But in the long runs I think we were very competitive."
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