IID Rolling Retests: Everything You Need to Know
Rolling retests are random breath tests required while you're driving. Here's how they work and how to handle them safely.
5-30 min
Frequency
4-6 sec
Breath Sample
~3 min
Time to Complete
What Is a Rolling Retest?
A rolling retest is a random breath test that the IID requires while you're driving. The purpose is to ensure you haven't started drinking after you started the car.
Why it exists
Without rolling retests, someone could pass the initial test sober, then have someone else take subsequent tests, or start drinking after starting the car.
When it happens
The device prompts retests at random intervals, typically every 5-30 minutes while the vehicle is running. Timing varies by state requirements.
What happens
The device beeps and displays a message like "TEST NOW." You have a few minutes to provide a breath sample. The car does NOT shut off if you fail or miss—but it is logged and reported.
How to Handle a Rolling Retest
Stay calm when prompted
The device will beep and display a message. You have 3-6 minutes (varies by state) to provide the sample.
Find a safe place to provide the sample
Pull into a parking lot, pull over to the shoulder, or wait until stopped at a red light. Never try to provide the sample while actively driving.
Provide a proper breath sample
Same technique as starting the car: steady breath for 4-6 seconds, not too hard, not too soft. The device will confirm when complete.
Wait for confirmation
The device will show PASS and you can continue driving. Continue your trip as normal.
Safety First
Never test while actively driving
Pull over or wait for a stop. Taking your eyes off the road and hands off the wheel to blow into a device is dangerous.
The car won't shut off
Modern IIDs do NOT turn off your engine if you fail or miss a retest. This would be a safety hazard. Instead, they log the event, honk the horn or flash lights, and report the violation.
You have time
You typically have 3-6 minutes to complete the test. Don't panic— find a safe place and complete it properly.
What Happens If You Miss or Fail?
If you miss the retest:
- • Event is logged as "missed retest"
- • Horn may honk or lights flash until you complete a test
- • Violation reported at next calibration
- • Car continues running
If you fail the retest:
- • Event is logged with BAC reading
- • Horn honks/lights flash until engine turned off
- • Serious violation reported
- • Car continues running—drive home safely
- • May result in IID requirement extension
Why the car doesn't shut off:
Shutting off a car while driving on a highway would create a serious safety hazard. Federal guidelines prohibit IIDs from disabling vehicles while in motion.
Tips for Handling Retests
Plan your trips
Expect retests on any drive. Factor in a few extra minutes for pulling over safely.
Know your device
Learn what the prompts look like and how much time you have. Practice during installation training.
Stay hydrated
A dry mouth can make it harder to provide a proper sample. Keep water in your car.
Don't panic
You have time. The device won't shut off your car. Find a safe spot and complete the test properly.
Retests with Camera-Equipped Devices
Some states require cameras on IIDs. During retests, the camera records who is providing the sample.
Why cameras exist:
- • Verify the driver is providing samples
- • Prevent having someone else blow for you
- • Provide evidence in case of disputes
What to know:
- • Make sure your face is visible when testing
- • Photos are reviewed at calibration
- • Mismatched photos = violation
IID Violations
Types and consequences
Tips & Best Practices
Avoid common IID problems
Sources
Information based on IID provider documentation and NHTSA guidelines as of January 8, 2026.