Defending champion Padraig Harrington, who was also part of the European's Ryder Cup win at Oakland Hills, posted a 2-under 68 to finish alongside Louis Oosthuizen and Alessandro Tadini at 7-under-par 133.
Jimenez won four times on the European Tour in the 2004 season and is halfway to kicking off the new campaign with another victory. The Spaniard was one stroke behind Adam Groom to start the day at Hong Kong Golf Club but quickly moved to 6 under with a birdie at the par-5 third.
While Howell was pacing the field throughout the day, Jimenez made his move down the stretch with back-to-back birdies from the 12th. He added a birdie at the 15th and matched Howell at minus-10 with a birdie at the par-4 17th.
Jimenez then birdied the par-4 18th to take sole possession of the lead.
'I try to be myself on the golf course, try to hit good shots and enjoy myself,' Jimenez said. 'I feel great on the golf course, I feel in the right mood. The game is there.'
Howell was on fire early on with an eagle at the third and a birdie at the par-4 fourth. The Englishman continued his fine play early on the back side with a birdie at the par-4 10th and another birdie at the par-5 12th.
The 29-year-old cooled off from that point on, however, and stumbled home with a bogey at the last for a round of 66.
Harrington picked up his first birdie of the day at the par-4 fourth but gave that shot back with a bogey at the very next hole. The Irishman recovered with a birdie at the sixth and managed a birdie at the 12th to stay within four of Jimenez.
'Miguel is probably the last player in the field I wanted to be four behind,' said Harrington. 'A lot of times you don't pay attention to the 36-hole leader, but I'm sure he is hoping that we are all paying attention to him.'
Groom had a roller-coaster round with an eagle, three birdies and five bogeys. He carded a 70 to join Gregory Havret, Lian-Wei Zhang and Bryan Saltus at 6-under-par 134.
The 36-hole cut fell at 2-over-par 142 with 81 players surviving for the weekend.