DUI ignition interlock — Tennessee Permit Test

DUI ignition interlock on the Tennessee permit test — 2 rules, each with the reason behind it and a question on it while it is fresh.

The rules

An ignition interlock device keeps a car from starting if the driver's BAC is too high.

A car that will not start cannot be driven drunk. The device does the job a promise cannot.

Only a motor vehicle equipped with a functioning ignition interlock device (which keeps a car from starting if the driver’s BAC is too high).

Tennessee Comprehensive Driver License Manual, p.82

A person with 2 DUIs in a 5-year period must drive with an ignition interlock device for 6 months after their driving privileges are reinstated.

Getting the license back is a second chance with a check built in. The interlock watches the first months back.

Please note that a person with 2 DUIs in a five year period MUST operate a motor vehicle with the ignition interlock device for six months after reinstatement of driving privileges.

Tennessee Comprehensive Driver License Manual, p.82

On the test

What does an ignition interlock device do?

Stops the car starting if BAC is too high. A car that will not start cannot be driven drunk. The device does the job a promise cannot. Tennessee Comprehensive Driver License Manual, p.82: “Only a motor vehicle equipped with a functioning ignition interlock device (which keeps a car from starting if the driver’s BAC is too high).”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.

Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.

What it costs

  • One payment, once — not a subscription. Nothing renews and there is nothing to cancel, for an exam you sit one time.
  • Free to start: a 10-question test and the first section of cards. No sign-up and no account.
  • Paying opens the rest of the cards, unlimited full-length practice tests, and retests built from exactly the questions you got wrong.
  • Every level up to Prepared — 3 tests passed in a row.
  • Do the work, fail the real exam, and we refund you.

All Tennessee permit topics

Where these come from

Every rule here is checked against Tennessee Comprehensive Driver License Manual, published by the Tennessee Department of Safety and Homeland Security, and against the state code itself. Last checked 2026-10-03.