Pettersen, a three-time winner this season, completed 36 holes at 3-under-par 141.
Eun Hee Ji fired a 4-under 68 Saturday to climb into second place at minus-2. Ji's 68 was the only round in the 60s in round two and is the low round of the week so far.
Former Women's British Open champ Jeong Jang (72) and Seon-Hwa Lee (71) are the final players in red figures at 1-under-par 143.
Women's World No. 1 Lorena Ochoa stumbled to a 3-over 75 in round two. She carded three bogeys, two birdies and a double-bogey as she dropped from a share of seventh into a tie for 12th.
Pettersen, who shared the lead after round one with Meena Lee, got her round going with a 4-foot birdie putt on the par-4 second. Pettersen moved to 5 under thanks to a birdie from 3 feet out on the par-3 fourth at Mauna Ocean Golf & Resort.
After three straight pars, Pettersen again found trouble at eight and nine. In the first round, she played those two holes in plus-3 and was only one shot better in the second round.
The 26 year old bogeyed both holes to slip into a share of the lead with Ji at minus-3. Pettersen birdied the 10th, but gave that stroke right back as she three-putted for bogey on 11.
Pettersen again got to minus-5 thanks to birdies on the 12th and 14th. She faltered down the stretch as she bogeyed 16 and 18 to close her round.
'It was very long, what else can you say? You just try to focus when it's your turn to play. You try to save the energy because it's such a long day in hard conditions,' said Pettersen of the cold, windy conditions that led to near six-hour rounds for many players. 'It takes a lot out of you.'
Ji, who has played in this event the last two years, is appearing in her fourth LPGA event of the season. After a birdie and a bogey on the front nine, Ji made her move around the turn.
She birdied the par-3 11th and came back with a birdie at 13. That got her to even-par for the championship.
Ji holed out for eagle on the par-4 14th. She gave a stroke back with a bogey at 16, but closed with a birdie at the last to end one back.
'On the back nine, my putter felt good, better than the front nine,' admitted Ji. 'The further I got into the back nine, the better it felt. I was able to play well.'
Hyun Hee Moon carded a 1-over 73 and is alone in fifth after two rounds at even-par 144. Sun Ju Ahn and Catriona Matthew are one shot back at plus-1.
Meena Lee struggled to a 5-over 77 to tumble into a share of eighth at 2-over-par 146. She was joined there by Shi Hyun Ahn (73), Na Yeon Choi (72) and Cristie Kerr (71).