Pierre Gasly’s session-ending issue during second practice for Formula 1’s Portuguese Grand Prix was started by an “electrical blackout” on his AlphaTauri car.

An action-packed afternoon session was interrupted by a red flag when Gasly’s AlphaTauri caught fire as he rounded the Turn 13 hairpin, with the car trundling to a complete standstill as the Frenchman lost all power.

Honda has launched a full investigation into its PU and chassis in order to diagnose the precise cause of the stoppage which resulted in Gasly sitting out the remainder of the day.

“As for Gasly’s incident in FP2, we know it was started because of an electrical blackout on the car,” Honda F1 engine chief Toyoharu Tanabe said.

“We are now carrying out a full investigation on the PU and chassis to try and identity the precise cause.”

Gasly is already on the limit of elements for his power unit allocation this season, meaning an automatic grid penalty would be triggered should any of the components need changing.

Asked when he first had a hint that something was wrong, Gasly replied: “Literally five seconds before I stopped.

“I just lost everything – the steering, all the electricity – and we’re still investigating to understand what happened but, obviously, there was quite a lot of fire at the back of the car and things burning, so we need to analyse and understand what happened.

“For sure it’s not ideal, especially because we could not run with the option tyre,” he added.

“We had only the base this morning, so, on a track like this, it’s never great. But that’s what we got, unfortunately, so we’ll try to get as much data as we can on Dany’s side.

“Base-wise it looked pretty decent all day long, but I’m still feeling not super comfortable with the car and we can improve it for tomorrow. FP3 will be an important one, because we need to recover these laps.”