Fox’s “House” got a post-Super Bowl bounce on Monday, but “The Chicago Code” fumbled away much of that young-adult audience and settled for ho-hum premiere results. CBS, boosted by “Two and a Half Men” and “How I Met Your Mother,” carried the night in key demos.

According to preliminary nationals from Nielsen, Fox kicked things off with a victory in all key categories at 8 o’clock with “House” (4.3 rating/12 share in adults 18-49, 12.3 million viewers overall), which grew 16% from its most recent original episode and hit a season high. It was followed by the new Shawn Ryan cop drama “The Chicago Code” (2.4/6 in 18-49, 9.4 million viewers overall), which improved upon the net’s performance in the hour this season with “Lie to Me” but had to settle for a third-place finish; it also dropped some in its second half-hour (2.3 vs. 2.6 in 18-49). On the same night a year ago, “House” did a 5.1 demo rating and lead-out “24” pulled a 3.3.

At CBS, which edged out Fox for the night’s lead in 18-49 and won by larger margins in both adults 25-54 and total viewers, “How I Met Your Mother” again impressed leading things off (second-place 3.8/11 in 18-49, 10.1 million viewers overall), matching its 18-49 rating and up 1 share point vs. the comparable night a year ago. It was followed by “Rules of Engagement” (3.2/8 in 18-49, 9.5 million viewers overall), “Two and a Half Men” (4.4/11 in 18-49, 15.1 million viewers overall) — the night’s No. 1 show in 18-49, 25-54 and total viewers — and “Mike and Molly” (3.6/9 in 18-49, 12.7 million viewers overall). Closing things out was “Hawaii Five-0” (2.8/8 in 18-49, 10.9 million viewers overall), which led the 10 o’clock hour across the board but was down from last year’s “CSI: Miami,” which benefited from a big “The Big Bang Theory” lead-in.

ABC’s “The Bachelor” (3.1/8 in 18-49, 9.7 million viewers overall) was in line with last week, placing third in 18-49 and first in 18-34 from 8 to 10 o’clock, and “Castle” (2.5/7 in 18-49, 9.3 million viewers overall) ran second in Monday’s final hour of primetime; latter drama matched its year-ago score even though “The Bachelor” was down from its scorching pace of last year.

NBC’s struggles on the night continued as “Chuck” (1.7/5 in 18-49, 5.4 million viewers overall), “The Cape” (1.3/3 in 18-49, 4.6 million viewers overall) and “Harry’s Law” (1.7/5 in 18-49, 9.1 million viewers overall) all wilted opposite all firstrun competition on the other major nets. “Harry’s Law” earned points for building on its low-rated, incompatible lead-in, but dropped 19% week to week.

At CW, “90210” (0.9/2 in 18-49, 1.8 million viewers overall) was up week to week and “Gossip Girl” (0.8/2 in 18-49, 1.6 million viewers overall) was mostly flat, with the shows combining for the net’s largest Monday audience (1.7 million) since early December.

Preliminary 18-49 averages for the night: CBS, 3.5/9; Fox, 3.4/9; ABC, 2.9/8; NBC, 1.6/4; Univision, 1.4/4; CW, 0.8/2.

In total viewers: CBS, 11.5 million; Fox, 10.9 million; ABC, 9.6 million; NBC, 6.4 million; Univision, 3.6 million; CW, 1.7 million.