It emerged last week that almost one million drink-driving tests recorded by police in the Republic of Ireland did not actually take place.
A separate error caused almost 15,000 wrongful traffic convictions.
Enda Kenny said his cabinet had agreed there should be an external examination of the Garda (Irish police) figures.
He said there should be an independent root and branch assessment of the force as it faces current and future challenges.
The commissioner has described the revelations as "totally unacceptable and not in keeping with the standards of a modern and professional police service".
While Mr Kenny admitted that his government had "serious concerns" and was "very unhappy" about the revelations, opposition parties have called on Ms O'Sullivan to resign.
Sinn Féin's deputy leader, Mary Lou McDonald, likened Gardaí (Irish police) to a fish "rotting from the head down" and said "the game is up" for the commissioner.
She said "malpractice was endemic".
Other opposition politicians described independent and external reviews as the favoured way of independent cabinet members of dealing with awkward issues.
On Sunday, the leader of the Fianna Fáil party said Ms O'Sullivan should consider her position.
Micheal Martin told Irish broadcaster RTÉ's This Week, that his party could not express confidence in Commissioner O'Sullivan, but added he did not want to embroil the Dáil (parliament) in the controversy.
Commissioner O'Sullivan was already facing questions over her leadership because of allegations of a smear campaign against a whistleblower, Sgt Maurice McCabe.
Sgt McCabe was one of two officers who raised concerns years ago about the alleged deletion of penalty points from the driving licences of well-connected offenders.
The Taoiseach (Irish prime minister) has told the Dáil that his government continues to have confidence in the Garda Commissioner, Noirin O'Sullivan.