P.K. Subban scored his first goal since March 18, and Mackenzie Blackwood made 19 saves for the Devils (14-20-6), who are 1-4-2 in their past seven.
"I think the thing that hurt us the most was just our puck management," Devils coach Lindy Ruff said. "Our first two trips moving inside the zone, we didn't get the puck deep. We kind of fueled their offense."
Sceviour scored twice in a span of 2:51 early in the first period. He gave the Penguins a 1-0 lead on a wraparound at 2:35 and made it 2-0 on a deflection from the slot at 5:26. He has three goals in his past two games.
"[Sceviour] is a guy that comes to the rink every day with a smile and works hard," Guentzel said. "It's always nice to see a guy like that get rewarded. I'm really happy for him and we're definitely lucky to have him."
Miles Wood deflected a shot from the slot to pull New Jersey within 2-1 at 17:14. It was his third goal in the past two games.
Guentzel scored on a snap shot to increase the lead to 3-1 at 19:20 of the second period. The Devils challenged for goalie interference, but the goal was confirmed following a video review and they were assessed a penalty for delay of game for the unsuccessful challenge.
"Pittsburgh came out really hard and that's what we wanted to do, but they got the first couple of pucks behind us, did a good forecheck and we didn't manage to get it out," Devils forward Andreas Johnsson said.
Guentzel made it 4-1 with a power-play goal at 1:19 of the third period.