GARDA Commissioner Martin Callinan has admitted there were "weaknesses" in the enforcement of the penalty points system.
But he insists the force has tightened up on procedures following the fallout from the controversy.
Speaking before the Dail's Public Accounts Committee, he said he was "not happy" about weaknesses highlighted by the Comptroller and Auditor General, and admitted there had been poor record-keeping on the Pulse computer system.
However, he said a number of measures had been introduced to "strengthen procedures" around the cancellation of fixed charge penalty notices.
He was called before the PAC after a garda whistleblower supplied the committee with a "box of evidence" highlighting alleged abuses of the system by gardai.
The commissioner said the changes, introduced last August following a report by Assistant Commissioner John O'Mahoney, had led to "greater oversight and auditing of the system".
"The impact of these measures has already been seen with internal audits of fixed charge penalty notice cancellations in November and December 2013 showing that 100pc of these cancellations were carried out within policy," he said.
Comptroller and Auditor General Seamus McCarthy told the committee he initiated an investigation into issues relating to the enforcement of penalty points after a garda whistleblower contacted him alleging members of the force had cancelled penalty points "corruptly or illegally".
He said the whistleblower alleged that people who had points cancelled had gone on to be involved in accidents which resulted in the deaths or injury of themselves or third parties.
He expressed concern about the absence of records in some cases examined, giving rise to suspicions they may have been cancelled without due cause.
The C&AG also said large numbers of summonses were never served.
"One in five unpaid fines did not go to court," he said.
Mr McCarthy said there was evidence that gardai had used discretionary powers to cancel points citing grounds not covered in garda regulations.
He also highlighted wide variations between different garda districts on the level of cancellations. For example, the level of cancellations in Ennis, Roscommon and Sligo was 50 times higher than in Birr.
Mr Callinan said he "could not be happy with some of the issues highlighted". However, he sought to downplay the extent of the problem. He said that during the period examined by Mr O'Mahoney, January 2009 to June 2012, 66,407 fixed charge notices were terminated – 4.5pc of those issued.
Mr O'Mahoney's report did not find evidence of widespread wrongdoing, but disciplinary procedures were brought against three officers.