Pettersson intercepted a diagonal outlet pass from Kings defenseman Dion Phaneuf just inside the Los Angeles blue line, skated in and beat Petersen with a wrist shot at 10:23 of the third period for a 3-2 lead.
It was the first shot on goal of the period for the Canucks.
"I cost our team one point for sure, if not two," Phaneuf said. "That's on me. That's a mistake that can't happen."
Motte scored shorthanded into an empty net with 1:19 left to make it 4-2.
Each team scored twice in the second period.
Luff scored his third NHL goal on a breakaway to tie the game 2-2 at 16:35.
"Both of their defensemen went to the wall and I saw it, so I burst out of the zone and [Carl Hagelin] made a nice saucer pass to me," Luff said. "I just threw a fake and [coach Willie Desjardins] tells us before the game what to do on goalies, and that was part of it, so it all worked out and we tied the game, but we've got to get the next goal and play with a lead."
Gaudette had given the Canucks a 1-0 lead at 5:12.
Jake Virtanen won the puck on the forecheck, and Nikolay Goldobin passed it back to Virtanen at the top of the left circle. Virtanen spun and passed it to Gaudette coming through the right hash marks and he scored on a one-timer.
"It felt good to get the monkey off the back there," said Gaudette, who was playing his 25th NHL game. "I just came off the bench and went hard to the net and it went in. ... I think it happened pretty fast. I didn't really process it right away but it's a great feeling, and it's a relief to get that first one for sure, and hopefully they start coming in bunches now."
Doughty ended an 0-for-16 stretch on the power play for the Kings when he scored on a slap shot through traffic at 7:23 to tie the game 1-1. It was his first goal in 14 games.
The Canucks came back with a power-play goal by Gagner at 12:18 to take a 2-1 lead.
Pettersson passed from the top of the right circle to Bo Horvat below the goal line, and Horvat made a quick pass to Gagner coming through the slot. Gagner scored his first goal of the season on a one-timer.