Thousands of computers and tablets that belong in city schools are either missing or unaccounted for — and the city has failed to create a centralized tracking system despite repeated warnings, according to a new audit from Comptroller Scott Stringer.

Just over 1,800 pieces of technology were missing from eight schools and one administrative office sampled by auditors, and another 3,500 in those nine locations were not sufficiently tracked, roughly 35 percent of the computers and tablets purchased for them.

If that sounds like déjà vu, it should: The findings are similar to a 2014 audit that showed significant amounts of missing technology — lost to theft or poor tracking — among a different sample of schools.

“I’m demanding that the [Department of Education] track these computers and tablets centrally,” Stringer said Wednesday. “I shouldn’t have to come back every two years to explain why this matters.”

Of the computers that were missing in the 2014 audit, the city could now only account for 13 percent of them, Stringer’s office said.

The audit raises questions about whether the education department can cost-effectively manage technology as it plans to expand access to it. Mayor Bill de Blasio has promised every student will have access to computer science education by 2025.

Education department spokesman Will Mantell called the report’s methodology “fundamentally flawed and unreliable,” arguing in part that the comptroller’s office didn’t always use the right inventory list or interview the correct staff. He noted the city is working to improve its inventory management.

The city “will continue to invest in cost-effective solutions that catalog and safeguard technology purchases in the best interests of students, schools and taxpayers,” Mantell added.