Fernando Alonso will use the Spec 2 Honda engine for the remainder of the Spielberg weekend.

Having trialled the latest upgrade in the Spaniard's car in the Friday sessions in Baku, for this weekend's race the Japanese manufacturer chose to issue both McLaren drivers with the new unit.

However late last night an issue was detected on Alonso's car and the decision was made to revert to the Spec 2 unit.

"Last night Honda detected an issue with Fernando's MGU-H, so they changed his PU," a McLaren spokesman told Pitpass.

"All newly fitted components have been used during previous grands prix so there will be no penalties. The ICE will be Spec 2 from day two in Azerbaijan."

Speaking at yesterday's press conference, Yusuke Hasegawa said first impressions of the upgrade were good.

"Of course car performance is not just coming from the PU, the chassis is also updated and it also depends on circuit characteristics," he said.

"But from the data point of view the engine also contributed to some of the lap time improvement so we are very happy about that."

Check out our Saturday gallery from Spielberg, here.