Italian GP: Jenson Button escapes DRS penalty in Monza practice

The McLaren drivers rear wing stayed open after the second activation zone that runs to the Ascari chicane and did not close until after the Parabolica.

With such use of DRS not allowed at any point of a grand prix weekend, Button was summoned to see the race stewards.

Investigations by McLaren showed that an issue with the low downforce rear wing specification had caused the flap to stay open.

McLaren sporting director Sam Michael said: "We had a problem with some parts that were fouling on each other, so we had a clash of two different things.

"It is because we don't run this wing or actuator anywhere else as it only runs at Monza.

"It was pretty straightforward to fix it, and we came in and pulled the parts off the car."

A report by the stewards said that they felt that McLaren's explanation meant that Button did not warrant a penalty.

"The stewards accept the evidence tabled by the team that, despite the DRS being shown as deactivated at the end of the first DRS zone (braking area for Turn 8) the hydraulic activation arm jammed against its carbon fibre cover, preventing deactivation of the wing element," the report said.