It’s the MTA’s “Number 1” priority.

Urine-detection technology could be coming to the yellow-soaked elevators of the Big Apple’s massive subway system, a top transit official said.

“We are actually going to be piloting a device that will alert — I won’t tell you what the smell is — but it will alert our cleaners about potential lack of cleanliness in elevators,” MTA New York City Transit President Rich Davey told City Council members on Monday.

Davey’s statement came in response to a question about the unsavory stenches that often greet straphangers when they enter the transit authority’s elevators.

The MTA has 353 elevators throughout the subway system, though the vast majority of stops do not have one.

New York would not be the first transit system to try spotting subway piss puddles before they ruin someone’s day, Davey said.

The subway agencies in Atlanta and Davey’s hometown of Boston have also tested the tech, according to the nonprofit news outlet The City.

Subway bathrooms have been closed since the start of the COVID-19 pandemic. MTA officials recently announced plans to reopen the facilities at nine stations, beginning in January.

Most subway elevators are pee-free and operational, according to MTA stats.

“I can tell you 97, 98% of our elevators in the last few months have been available.” Davey told council members.