Driving licences are being stripped from 94 people after an interpreter admitted selling candidates the answers to a written test.
It comes as the UK government consults on whether to scrap rules allowing those who do not speak English or Welsh to take tests in other languages.
Allyson Ng, from Bristol, was jailed at Cardiff Crown Court for fraud.
Since 2009 she had interpreted on 123 theory tests, and the DSA says it is continuing to revoke 94 of these.
While the majority of the fraudulent tests were in Cardiff, a small number were in Birmingham.
Last week Ng, who lives in Bristol, was jailed for a year after admitting conspiring to defraud the DSA, which is in charge of driving tests.
She was arrested at the Cardiff theory test centre in October 2012.
Ng charged £110 a time for translation, and the agency said it became suspicious after a surge in the number of her customers in the second half of 2011.
Any drivers who have got their licences as a result of the fraud will lose them and will have to take the theory test again.