Jenson Button has been hit with a 15-place grid penalty for the Monaco Grand Prix
Button, 37, is back on the Formula One grid in Monte Carlo this weekend following Fernando Alonso's decision to take part in the Indianapolis 500.
McLaren's season has been derailed by a series of problems with their engine supplier Honda. The British team prop up the constructors' championship having failed to score a single point this year.
And following a series of changes to the parts on Button's Honda engine after an issue was detected following second practice at the principality on Thursday, the Englishman is poised to start his one-off race from the back of the pack.
- Monaco Grand Prix practice: Why is it on a Thursday? Reason revealed
- Lewis Hamilton breaks THIS record in Monaco Grand Prix Free Practice 1
Jenson Button has been hit with a grid penalty in Monaco
"We have changed Jenson's MGH-U/TC after detecting an issue with his MGU-H after FP2," a Honda spokesperson said ahead of final practice.
"The MGU-H/TC will be Jenson's fifth which means he will receive a 15-place grid penalty for the race."
Button was 12th-fastest in practice on Thursday ahead of the 306th race of his grand prix career.
Double world champion Alonso will be back in the McLaren cockpit for the next round in Canada.
The Spaniard will start from fifth for his rookie appearance at the Indy 500 on Sunday.