Five police staff are being investigated by an internal integrity group for misusing software that recognises vehicle number plates.
An audit found two of them used the system to track their own cars.
About 6000 staff can search third-party CCTV for previously captured footage of vehicles, while about 1000 can also track them in real time.
Police said the review of 350,000 searches showed overall staff are using the systems as intended.
It found 120 people looked up their own vehicles, but the police had not investigated if they broke the rules.
Police said they were tightening up controls to better prevent misuse and errors.