Disney scored an animated hit in 2012 with “Wreck-It Ralph,” a nifty bit of manic nostalgia about characters from old-style arcade video games, but stumbles with this sequel, which takes the main characters into the Internet age with a thud. Curiously smug and overly self-aware, “Ralph Breaks the Internet” is exceedingly busy, but lacking in the heart and humor that were hallmarks of its predecessor.

The script by director Phil Johnston and Pamela Ribon, based on an idea by co-director Rich Moore, finds buddies Ralph (voiced by John C. Reilly) and Vanellope (Sarah Silverman) still ensconced in games at the emporium run by Mr. Litwak (Ed O’Neill), but feeling rather differently about their daily duties. Ralph enjoys the sheer predictability of routine in the Fix-It Felix game, and of the off hours he spends quaffing root beers along with Vanellope, but she’s bored driving the same course constantly in Sugar Rush.

So good old Ralph decides to make a new track for her in the game, and while she takes to it with glee, her enthusiasm is at odds with the intention of the human players, who yank the steering wheel off the game. Replacement cost would be prohibitively high—the rare wheel would have to be bought at a premium on something called eBay—so Litwak prepares to pull the plug on Sugar Rush permanently.

That would be a disaster, so Ralph decides to rectify his previous disastrous mistake. By using one of Litwak’s newest additions—WiFi—he determines to go to the Internet, whatever that might be, and secure the needed part. Vanellope insists on tagging along, and before long they find themselves in a massive metropolis that represents the conglomeration of all websites, ads, controlling algorithms and user data—a not terribly imaginative way of visualizing the Internet—where, not comprehending the notion of an auction, they bid against one another for the steering wheel on eBay and win it, but at an exorbitant price they will have to pay in forty-eight hours.

That leads the duo to seek out ways of raising money that leads them to an online game called Slaughter Race where Vanellope finds her heroine in Shank (Gal Gadot), a driver who loves taking risks. Ralph keeps his eye on the prize, following the advice of BuzzzTube algorithm mistress Yesss (Taraji P. Henson) to star in a series of yuk-producing videos that will go viral, get lots of “likes” and thus rake in cash. Most of them are—to put it mildly—uninteresting, but the notion that users are out there looking for—and chortling over—such stuff seems to be presented as benign rather than unnerving. (Even pop-up ads are treated here as helpful stuff.)

Vanellope, meanwhile, not merely dreams of doing what Shank does, but wanders into the Disney site, where the company gets a chance to parade its wares, from “Star Wars” to the Marvel Universe, with a bit of gentle ribbing that can’t disguise the fact that what we’re talking about is a large dose of product placement. (Look, we can make fun of ourselves even while promoting our goods. “The Simpsons,” on which Moore previously worked, has gone a lot further needling Fox over the years.)

There is, to be sure, an oasis in the midst of this corporate back-patting when Vanellope stumbles into a roomful of Disney princesses. Again, the gag isn’t all that new; send-ups of the princess mentality have been fairly common in animated flicks for a decade. And you might wonder whether, in the back of the makers’ minds, there might be lurking a commercial thought: remember, girls, princess paraphernalia is available at the Disney Store!

Still, the princess episode is a high point here, especially since it leads to the movie’s big musical number, Vanellope’s “A Place Called Slaughter Race”; one can also appreciate a riff on search engines with a character called KnowsAll (Alan Tudyk), who constantly predicts the continuations of whatever items you’re asking about.

Low ones come in an effort to lighten up the Dark Web by introducing a mean-spirited blob called Double Dan (Alfred Molina) as its controller, and the big finale, when a gigantic Ralph figure, composed of innumerable little clones swarming together like some swirling, destructive King Kong, threatens the very existence of the World Wide Web. (Meanwhile Jack McBrayer’s Felix and Jane Lynch’s Calhoun, unhappily, get fobbed off with a subplot that spins its wheels but goes nowhere.)

Of course “Ralph Breaks the Web” is as polished as can be—the animation is splendid and the voicework outstanding. Compared to the original “Wreck-It Ralph” or “Zootopia,” on which Johnston and Moore also worked together, however, it comes across distinctly third-best, more successful as an exercise in merchandising than in imaginatively cheeky world-building.