The long-delayed launch of the MTA’s East Side Access service could be pushed beyond January due to an issue with an exhaust fan in the new station, officials said Wednesday.

The latest problem stems from one exhaust system in the new terminal that isn’t pulling in enough air because of a “counteracting air flow” in Grand Central Terminal, MTA Chairman Janno Lieber said.

Lieber wouldn’t commit to a new opening date, and said crews were working to fix the problem.

Lieber for years promised to open the new service — which aims to bring LIRR trains into a new station named “Grand Central Madison” that sits 150 feet beneath Grand Central Terminal — by the end of 2022.

“It’s a code issue, it’s a safety issue,” Lieber said Wednesday. “It’s as if you had a walkthrough of a house that was done and you can smell the new house and you can smell the new paint, and they told you there’s still a village code inspection that needs to take place.”

It’s the latest hiccup for a project long plagued by mismanagement. In 2001, the service was expected to open in 2011 at a cost of $4.3 billion. Nearly 12 years later, the price tag sits at $11.6 billion, federal records show.

Lieber said he isn’t sure who’s to blame for the most recent delay, but wants to make sure the MTA doesn’t pay anything extra if one of the agency’s contractors made an engineering error.

“I’m not paying for extra work that is necessitated because somebody, however well intentioned, didn’t design something perfectly. And we’ll see what happens,” he said.

The MTA last month announced the full service at the station would not launch until 2023. Instead of operating up to 24 trains per hour to and from the new station, the station was slated to launch by the end of December with no more than two trains per hour between Grand Central Madison and Jamaica Terminal in Queens.

The MTA pushed back the truncated launch in the final days of the year.

The project faced last-minute drama that threatened to delay the opening once before. The MTA was granted a last-minute waiver from federal officials in December over mandatory track safety technology that was not yet installed. The agency has until Feb. 25 to complete that work.