The jail time ends. The fine gets paid. The ignition interlock is the part of an Arizona DUI that stays in your daily life for a year or more — in your car, in front of passengers, on every trip to work. It’s also the requirement people understand least going in, and the one where avoidable mistakes quietly extend the sentence. Here’s how the device actually works, what it costs, how long you’ll have it, and the compliance traps worth knowing before installation day.
The clock may not start when you think. Arizona generally measures the interlock period from the date your driving privilege becomes eligible for reinstatement — or the date MVD receives the report of your conviction, whichever is later. Not from your arrest, and not from your conviction date. Delays in the paperwork can push your end date later than you expect.
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How long you’ll have the device
The requirement comes from A.R.S. § 28-3319, and the duration scales with the offense:
- Standard first DUI (0.08–0.149): 12 months.
- Extreme DUI (0.15–0.199): 12 months.
- Super Extreme DUI (0.20+): 18 months.
- Aggravated (felony) DUI: 24 months or longer, following a three-year license revocation.
- Second offense: 12 months, following a one-year revocation.
The device is required in every motor vehicle you operate — not just the car you were arrested in. That detail catches people who share vehicles with a spouse or drive a second car occasionally.
What it costs
Interlock costs aren’t set by statute; they’re set by the certified providers, and you pay them. Expect roughly $70 to $100 per month for the lease and monitoring, plus installation and removal fees, with calibration or service visits typically bundled into the monthly rate. Over a 12-month standard requirement that lands somewhere in the neighborhood of a thousand dollars or more all in — a real cost that most people don’t factor in when they’re thinking about fines and jail. These are market estimates rather than fixed prices, so it’s worth calling two or three certified installers.
How the device works day to day
You blow into the unit before the car will start. If it reads alcohol above the set threshold, the vehicle won’t start, and the event is recorded. Most Arizona units also require rolling retests — prompts to provide a breath sample while you’re driving — which exist to prevent someone else from blowing to start the car. A missed or failed rolling retest generally doesn’t shut the engine off mid-drive (that would be dangerous); it logs the event and typically triggers an alarm until you stop and provide a sample.
Everything is logged. The unit records every start attempt, every reading, every retest, and every tamper alert, and that data goes to MVD.
The reporting rules that trip people up
Arizona requires ongoing proof, not just installation. Under § 28-3319 you must provide MVD with proof of installation of a functioning certified device, and then proof of compliance and calibration at least once every 90 days throughout the required period. Miss a calibration appointment and you’re out of compliance — which can extend your interlock period or trigger a further suspension, turning an administrative slip into months of extra time.
Set calendar reminders for calibration visits. It sounds trivial; it’s the most common reason people end up with the device longer than the statute required.
Violations are their own offense
Tampering with, circumventing, or bypassing an interlock is separately unlawful in Arizona, as is having someone else blow into the device for you — and that includes the person who blows. Arizona addresses interlock use and violations in A.R.S. § 28-1461 and § 28-1464. Beyond the new charge, a violation typically extends the interlock period and can trigger additional license action. Given that the whole point is getting through the period and being done, the math on circumvention never works.
Interlock and driving during a suspension
The interlock is also the mechanism behind the SIIRDL — the Special Ignition Interlock Restricted Driver License — which can let you drive an interlock-equipped vehicle during a suspension period. Since 2023 it permits general driving rather than restricting you to work and school. One significant caveat: applying for a SIIRDL generally waives your right to the admin per se hearing, so it’s a decision to make with advice rather than reflexively. Our license suspension and MVD hearing guide covers that tradeoff in detail.
Flagstaff practicalities
Two things specific to living up here. First, cold weather: interlock units live in an unheated car at 7,000 feet, and extreme cold can affect device behavior and make providing an adequate breath sample harder on winter mornings. Ask your installer about cold-weather guidance rather than discovering it at 6 a.m. in January. Second, provider access: certified installation and calibration locations are more concentrated in the Phoenix metro, so confirm where your nearest Flagstaff-area service point is before you choose a provider — a 90-day calibration requirement is much easier to meet when it isn’t a two-hour drive.
For how the interlock fits into the overall penalty picture, see our main Flagstaff DUI guide, or the first-offense guide if this is your first case.
Frequently asked questions
How long will I have an ignition interlock in Arizona?
Generally 12 months for a standard or Extreme first DUI, 18 months for Super Extreme, and 24 months or more for an aggravated (felony) DUI. The period is typically measured from when your privilege becomes eligible for reinstatement or when MVD receives the conviction report, whichever is later.
How much does an ignition interlock cost?
Roughly $70 to $100 per month plus installation and removal fees, depending on the certified provider. Over a 12-month requirement the total commonly exceeds a thousand dollars. Prices are set by providers, not by statute, so it pays to compare two or three.
Do I need one in every car I drive?
Yes — Arizona requires a certified device in each motor vehicle you operate, not only the vehicle involved in the arrest. Occasional use of a second or shared vehicle is a common compliance gap.
What happens if I miss a calibration appointment?
You fall out of compliance. Arizona requires proof of compliance and calibration at least every 90 days, and missing it can extend your interlock period or lead to further license action — one of the most common self-inflicted problems in this process.
Can someone else blow into the device for me?
No. Circumventing or tampering with an interlock is separately unlawful in Arizona, for the driver and for the person providing the sample, and it typically extends the interlock requirement on top of any new charge. Rolling retests exist specifically to detect this.
Will the car shut off if I fail a rolling retest?
Generally not mid-drive, for obvious safety reasons. A missed or failed retest is logged and usually triggers an alarm prompting you to stop and provide a sample, and the event is reported.
Can I drive during my suspension with an interlock?
Possibly, through a Special Ignition Interlock Restricted Driver License (SIIRDL), which since 2023 allows general driving in an interlock-equipped vehicle. Note that applying generally waives your right to the MVD admin per se hearing, so weigh that with an attorney first.
Related guides
Questions about your interlock requirement? Free and confidential
Whether you’re facing a charge or trying to sort out compliance, we’ll connect you with an independent licensed Arizona attorney who handles DUI cases for Coconino County drivers.
Sources & Corrections
Primary sources checked for this page on July 31, 2026:
- A.R.S. § 28-3319 — Ignition interlock device requirement; proof of installation and calibration
- A.R.S. § 28-1461 — Use of certified ignition interlock devices (and § 28-1464, violations)
- Arizona MVD — Ignition Interlock FAQ
- Arizona MVD — SIIRDL
See an error on this page? Email corrections@flagstaffazattorney.com — corrections are reviewed and logged. Our corrections policy.
Not legal advice. The Flagstaff Legal Resource Center is an independent referral service operated by Wilder West Assets LLC — not a law firm. Interlock costs are provider-set market estimates, not statutory figures, and requirements change — verify current rules and pricing with MVD and certified providers. No attorney-client relationship is created by using this site. Verify any attorney’s credentials through the State Bar of Arizona.