Alpine's running at this week's opening pre-season test has ended early after a stoppage for Fernando Alonso.
Alonso, having already taken a trip through the gravel trap, brought out the red flags when he ground to a halt in the final sector during Friday morning's session at the Circuit de Barcelona-Catalunya.
Smoke billowed from Alonso's car as he watched on from the sidelines, with Alpine initially explaining that "a loss of pressure" was to blame, without going into any specific details.
Alonso and Alpine's Barcelona test ends early
After inspections in the garage, Alpine confirmed the root cause, and the end of their test, in a brief statement.
"After further investigations in the garage following Fernando Alonso's on-track stoppage earlier this morning, the team can confirm the issue was a problem with the hydraulics," read the statement.
"A minor sealing issue led to a fire in the back of the car. Repairs on the car will continue, and as a result, we won't be running for the remainder of the day."
F1's next pre-season test session will be held in Bahrain from 10-12 March.
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