Ignition Interlock Device — Florida DUI

Under Florida Statute § 316.193(2)(a)(3), an ignition interlock device is mandatory for any first DUI conviction with a BAC of .15 or higher or a minor in the vehicle, and for all second and subsequent DUI convictions regardless of BAC. The device prevents the vehicle from starting if alcohol is detected in the driver’s breath sample and requires rolling retests while driving. Installation costs $70–$150 per month including device rental and calibration. Tampering with the device or having another person provide the breath sample is a first-degree misdemeanor. Understanding the interlock requirement — and how it affects your daily life — is part of understanding what a DUI conviction actually costs you.

Legally reviewed by Tonmiel Rodriguez, Board Certified Criminal Trial Lawyer — last reviewed June 2026.

When Is an Ignition Interlock Device Required After a Florida DUI?

Florida law mandates ignition interlock in three specific situations under § 316.193(2)(a)(3):

• First DUI, BAC .15 or higher: Mandatory ignition interlock for a minimum of 6 months as a condition of any driving privilege, including hardship license.
• First DUI with a minor in the vehicle: Mandatory ignition interlock for a minimum of 6 months regardless of BAC.
• Second DUI conviction (any): Mandatory ignition interlock for a minimum of 1 year.
• Third or subsequent DUI conviction: Mandatory ignition interlock for a minimum of 2 years.

For a first DUI conviction with a BAC under .15 and no minor in the vehicle, ignition interlock is not automatically required by statute — but the court has discretion to order it as a condition of probation. The interlock must be installed on every vehicle the convicted person owns or regularly operates, not just the vehicle involved in the DUI.

How Does a Florida Ignition Interlock Device Work?

The ignition interlock device is a breath-testing unit wired directly into the vehicle’s ignition system by a DHSMV-approved service provider. Before the engine will start, the driver must provide a breath sample with a reading below the set threshold (typically 0.025 BAC — well below the legal limit of .08). If the sample exceeds the threshold, the vehicle will not start and the failed attempt is logged in the device’s memory, reported to the monitoring authority, and transmitted to the DHSMV. Once the vehicle is running, the device requires periodic rolling retests while driving — typically every 5 to 15 minutes — to confirm the driver has not consumed alcohol after starting the vehicle. A failed rolling retest does not immediately shut off the engine (which would be dangerous), but it triggers a warning, activates the horn and lights, and logs the violation.

How Much Does a Florida Ignition Interlock Device Cost?

The total monthly cost of a Florida ignition interlock device is $70–$150, which typically includes:

• Installation: One-time fee of $75–$150 at an approved service provider.
• Monthly device rental: $60–$90 per month.
• Monthly monitoring and calibration: Required at an approved service center every 30–60 days; fees are typically included in the monthly rate or charged separately at $20–$40 per visit.
• Removal fee: $75–$100 at the end of the required period.

Over a 6-month mandatory period, total costs typically run $600–$1,100. Over a 2-year period, the total cost is $2,000–$4,200. These costs are on top of all other DUI fines, court costs, DUI school fees, FR-44 insurance premiums. A reckless driving reduction eliminates the interlock requirement entirely.

What Are the Violations for a Florida Ignition Interlock Device?

The DHSMV monitors interlock compliance through monthly reports from the device’s service provider. Violations reported to DHSMV include:

• Failed startup test: A breath sample above 0.025 BAC when attempting to start the vehicle.
• Failed rolling retest: A breath sample above the threshold during a driving retest.
• Missed retest: Failure to provide a rolling retest sample within the required time window.
• Tampering or circumvention: Any attempt to defeat, disable, or bypass the device — including disconnecting the power, running a different fuel source, or using a compressed air cannister — is a noncriminal traffic infraction under § 316.1937, punishable by a 1-year license revocation (5 years for a second violation). Having another person blow into the device to start it is also a violation of § 316.1937.
• Missed calibration appointment: Failure to bring the vehicle to an approved service center within the required window extends the interlock period.

A violation reported to DHSMV can result in extension of the interlock period, revocation of hardship license privileges, or a violation of probation if the interlock was ordered as a probation condition.

How Do You Get the Ignition Interlock Device Removed in Florida?

To have the ignition interlock device removed in Florida, you must: (1) complete the full mandatory interlock period without any violations reported to DHSMV; (2) obtain a court order or DHSMV authorization confirming the period is complete; (3) return to an approved service provider for removal; and (4) pay the removal fee ($75–$100). If violations occurred during the interlock period, DHSMV may extend the required period — sometimes significantly. The DHSMV tracks interlock compliance through the approved service provider’s monthly reports, not through self-reporting. You cannot simply stop using the device and claim the period is complete; the service provider’s records are the official record.

Is There an Employer Vehicle Exemption for Florida Ignition Interlock?

Yes — there is a limited employer vehicle exemption under § 316.1937(5). If your employment requires you to operate a vehicle owned by your employer, and the vehicle does not have an ignition interlock device installed, you may operate that employer-owned vehicle without the interlock if your employer provides written documentation that the employer is aware of the interlock requirement and permits you to operate the vehicle anyway. The exemption does not apply to vehicles you own or regularly operate personally. It applies only to employer-owned vehicles operated in the course of employment. The exemption must be documented and you cannot use it to circumvent the interlock requirement on vehicles you own or control outside of work.

Does a Reckless Driving Plea Avoid the Ignition Interlock Requirement?

A reduction from DUI to reckless driving under § 316.192 eliminates the ignition interlock requirement entirely, because reckless driving carries no mandatory interlock under Florida law. This is one of the most significant practical benefits of a DUI reduced to reckless driving — beyond the lower fines, shorter probation, and reduced insurance impact, eliminating the interlock saves $600–$4,200 in device costs and removes a significant daily inconvenience. Whether a reduction is achievable depends entirely on the facts of the case, the strength of the defense, and the prosecutor’s assessment of their evidence.

The Installation Process — What to Expect at an Approved Vendor

After the court orders ignition interlock, DHSMV requires installation within a specific timeframe (usually tied to hardship license reinstatement or as a probation condition deadline). Installation must be performed by a DHSMV-approved service provider — not any auto shop. The installation appointment typically takes 1–2 hours. The technician wires the device into the vehicle’s ignition system at the starter circuit, installs the handset near the driver’s position, and performs an initial calibration and verification test. You receive documentation of the installation, which must be provided to your monitoring authority and DHSMV.

In Polk County and the greater Lakeland/Bartow area, approved interlock providers include national chains such as Intoxalock, LifeSafer, Smart Start, and Guardian Interlock. Locations operating in the area include shops in Lakeland, Winter Haven, and Haines City. I advise clients to verify current DHSMV approval status before scheduling installation, as approved vendor lists are periodically updated. Installation at an unapproved vendor does not satisfy the court order and can result in a probation violation.

Calibration Schedule and Rolling Retest Requirements

Florida DHSMV requires calibration and monitoring of ignition interlock devices every 30 to 60 days. Calibration is performed at the same approved service center where the device was installed. At each calibration visit, the technician downloads the device’s event log — recording every startup test, every rolling retest, and every violation — and transmits the report to DHSMV. You cannot skip or delay calibration appointments: a missed appointment is a violation logged in the same system as a failed test, and it will be reported to the monitoring authority and potentially to the court if the interlock is a probation condition.

Rolling retests occur at random intervals while the vehicle is in motion — typically every 5 to 15 minutes after the initial startup test. The device will beep or flash to signal a retest is required. The driver has a short window to provide a breath sample while continuing to drive safely. If the sample exceeds 0.025 BAC or if no sample is provided within the window, the device logs a violation, activates the horn and lights, and a tamper warning appears on the handset. The engine does not stop — shutting off a moving vehicle would be dangerous — but the logged violation is transmitted at the next calibration visit. Multiple missed retests or failed rolling tests will trigger DHSMV consequences.

What Actually Triggers a Violation — Common Mistakes to Avoid

Clients are sometimes surprised by what triggers a violation flag. Beyond alcohol consumption, the following can cause false or unexpected readings:

• Mouth alcohol from mouthwash or breath spray: Many mouthwashes contain significant alcohol. Use only alcohol-free dental hygiene products while under an interlock order. Even a small amount of residual mouth alcohol from mouthwash can exceed the 0.025 startup threshold.
• Food residue and fermentation: Bread, certain fruits, and yeast-containing foods can produce low-level fermentation in the mouth that triggers false readings. Rinse your mouth with water before providing any breath sample.
• Hyperventilating before a test: Some people unconsciously hyperventilate when nervous about the test — hyperventilation actually lowers the breath alcohol reading. Forced hyperventilation to manipulate results is still treated as a circumvention attempt if the pattern is detected.
• Attempting to blow without fully seating the mouthpiece: Improper technique can result in an incomplete sample, which the device logs as a missed test.

Related DUI Topics

• DUI in Florida — Overview
• DUI Penalties in Florida — Complete Guide
• Hardship License After DUI — Florida
• DUI Reduced to Reckless Driving
• DUI Administrative Suspension — Polk County
• First DUI in Florida
• DUI Defenses — How to Fight DUI Charges

Frequently Asked Questions — Florida Ignition Interlock Device

When is an ignition interlock device required in Florida?

Under § 316.193(2)(a)(3), ignition interlock is mandatory for: any first DUI with a BAC of .15 or higher (6 months minimum); any first DUI with a minor in the vehicle (6 months minimum); any second DUI conviction (1 year minimum); and any third or subsequent DUI conviction (2 years minimum). For a standard first DUI under .15 with no minor present, interlock is not statutorily required, though the court may order it as a probation condition.

How much does a Florida ignition interlock device cost per month?

Total monthly costs run $70–$150, including device rental ($60–$90/month), required calibration visits every 30–60 days, and monitoring fees. Over the mandatory minimum period, expect total costs of $600–$1,100 for a 6-month requirement and $2,000–$4,200 for a 2-year requirement. Installation and removal fees add another $150–$250.

Is tampering with a Florida ignition interlock device a crime?

Yes. Under § 316.1937, tampering with, circumventing, or attempting to bypass an ignition interlock device is a first-degree misdemeanor, punishable by up to 12 months in jail and a $1,000 fine. Having another person provide the breath sample to start the vehicle is also a first-degree misdemeanor. Both the driver and the person who provided the sample can be charged.

Can I drive my employer’s vehicle without an ignition interlock installed?

Yes, with proper documentation. Under § 316.1937(5), you may operate an employer-owned vehicle without interlock if your employer provides written documentation confirming awareness of the interlock requirement and permission to operate the vehicle. This exemption applies only to employer-owned vehicles driven in the course of employment — not to your personal vehicles or any vehicle you own or regularly operate.

What happens if I fail a rolling retest on my Florida ignition interlock?

A failed rolling retest above 0.025 BAC is logged by the device and reported to DHSMV through the service provider’s monthly report. The immediate vehicle response is a warning alarm — horn and lights — but the engine does not shut off. The DHSMV report can result in extension of your interlock period, revocation of hardship driving privileges, or a violation of probation if interlock was a probation condition. Multiple violations can significantly extend the total time you are required to use the device.