Scott McLaughlin has been relegated to the back of the grid for this afternoon's Sandown 500, after his DJR Team Penske team was fined AU$30,000 for breaching rules at Bathurst.

The rule breach was a result of McLaughlin's engine exceeding "the maximum permitted valve lift prescribed in the car's Engine Specification Document," leaving the Confederation of Australian Motorsport to fine the team, retroactively disqualify McLaughlin from Bathurst qualifying and the shootout, and send him and co-driver Alex Premat to the back of the grid for the Sandown race.

McLaughlin was stripped of his Bathurst pole and lap record, but his Bathurst win - which came after an engine change - remains.

DJR Team Penske apologised for the breach, and provided an explanation.

"The engine in question experienced a mechanical problem during practice and qualifying. Following the Top Ten Shootout, we were granted permission by the Head of Motorsport to change the engine prior to the race.

"The steward's report confirmed that there was clearly no intent from our team to circumvent the rules and there was no evidence that we benefited from any performance advantage.

"We apologise to Scott, Alex, our partners and our supporters, and we will continue to focus on winning our second consecutive Supercars Championship."

It's the second major penalty that the team incurred at Bathurst, after the $250,000 fine and 300-point team penalty handed down for Fabian Coulthard slowing down under safety car near the end of the race.

Despite starting from the back of the grid this afternoon, McLaughlin only needs to finish the race to lock up a second consecutive Supercars Championship.