In Q1, Wehrlein touched the grass on his approach to Turn 1 and was pitched into a spin, with the car sliding into the barriers and breaking the rear wing.

Motorsport.com understands there was significant damage to the rear of the car and, after an inspection of the gearbox, Sauber decided a fresh unit was required.

Under F1's sporting regulations, drivers need to run the same gearbox in six consecutive events or take a five-place penalty.

Wehrlein was already set to start from the back but the team has yet to decide whether he will take up the final grid slot or start from the pits.

Wehrlein took the blame for the incident, admitting it was his mistake as he was "overdriving" the car.

"I tried to push to extract the maximum but obviously it was my mistake in Turn 1," he told Motorsport.com. "I'm sorry for the mechanics because at the moment they are working so much - it was simply my mistake.

"I was overdriving the car because already the lap before I had a few moments out of the corners. I'm just trying really hard to extract the maximum out of the car.

"We can see the gap to the cars in front, I'm just trying hard, and the last lap it was too much."

Wehrlein has reverted to an older version of the team's Canada-spec rear wing, as the team does not have a spare of the new version it brought to Montreal.

Teammate Marcus Ericsson will continue to run the latest version but it is believed the part has not delivered the gains Sauber had expected.

Sauber was also hoping to unlock the potential of its Monaco upgrade package in Canada, but so far is at a loss as to why it is not delivering the performance the data has suggested it can.

"Since Monaco, we have had the new aero package and we expected a good step but at the moment we can't see it," said Wehrlein. "We don't know if it is track-related or if it is tyre-related.

"From the numbers, everything is working, as expected. We can see the gains, but we can't see the lap times. We're half a second off the teams ahead of us.

"If it's a normal simple race without DNFs or issues on other cars, it will be difficult."