What Is an Ignition Interlock Device?
“I just got a DUI. What is an Ignition Interlock Device, and why do I have to install one on my car?”
Installing an Ignition Interlock Device (IID) on your vehicle is a common legal or administrative requirement for drivers after a DUI. An Interlock Device requires the driver to blow into the device before starting the vehicle and while driving.
Here’s a little bit more about how these devices work, and how you can find one that fits your needs — including Smart Start’s affordable, user-friendly options for Ignition Interlock Devices near you.
Here’s a little bit more about how these devices work, and how you can find one that fits your needs — including Smart Start’s affordable, user-friendly options for Ignition Interlock Devices near you.
How Does an Ignition Interlock Device Work?
First things first — the definition of an Ignition Interlock Device is:
An Ignition Interlock Device (IID) is a small handheld device that connects to the ignition system of a vehicle. Before starting the vehicle, the driver has to blow a breath sample into the device. If the IID registers breath alcohol content (BrAC) over a set point (determined by state or local laws) in the breath sample, the vehicle’s ignition will not start. (See How Does a Breathalyzer Work? to learn more about what’s going on inside an IID.)
Most IIDs also require drivers to complete rolling retests, meaning the driver is required to test again at random intervals during their drive. Rolling retests verify a driver’s BrAC remains below the predetermined standard during their drive and helps prevent drivers from consuming alcohol after starting their vehicles. We always recommend pulling over and stopping to complete a rolling retest, but note that a Smart Start IID will never shut off the engine while you are driving. You can learn more about rolling retests here.
Most IIDs also require drivers to complete rolling retests, meaning the driver is required to test again at random intervals during their drive. Rolling retests verify a driver’s BrAC remains below the predetermined standard during their drive and helps prevent drivers from consuming alcohol after starting their vehicles. We always recommend pulling over and stopping to complete a rolling retest, but note that a Smart Start IID will never shut off the engine while you are driving. You can learn more about rolling retests here.
Our experienced team is here to help! After your Smart Start IID installation, you’ll receive a hands-on demonstration of how to use your IID — and our 24/7 multilingual Program Advisors have you covered if you ever have questions.

When Is an Ignition Interlock Device Required?
Interlock Devices are a common consequence following a DUI. They’re especially common when a DUI includes aggravating circumstances, such as repeated DUI offenses, minors present in the vehicle, or accidents and injuries.
The conditions of your IID requirement will be different, depending on your specific circumstances, and will vary by state. In most cases, you’ll have to:
The conditions of your IID requirement will be different, depending on your specific circumstances, and will vary by state. In most cases, you’ll have to:
- Keep the IID installed for a certain amount of time (often one year)
- Avoid violations, such as providing a sample that’s over the device’s limit
or failing to complete a rolling retest - Pay for the device lease and installation using your own funds
- Regularly report to a service center for calibration
How Much Does An Ignition Interlock Device Cost?
Since paying for the IID will be your responsibility, it’s logical to wonder how much an IID costs. While costs will vary depending on the state you live in and the length of your requirement, among other factors, they will typically include:
- Enrollment fee to secure your installation appointment
- A monthly lease payment for the equipment
- Installation fee
- Calibration fee
- Administration closing fee and labor fee upon removal
If installing and leasing an IID is a financial challenge for you, remember that many states offer financial assistance for IIDs. See our guide to IID costs and pricing for more information, or speak with a Program Advisor at
(800) 831-3299 for a quote today.
Find an Ignition Interlock Device Near You
Contact one of Smart Start’s Program Advisors at
(800) 831-3299 today to set up your installation appointment. Our nationwide network of service centers with qualified technicians makes it easy to find an IID near you, with convenient same-day IID installation available in many cases.Our Program Advisors are well-informed, ready to help, and non-judgmental — just call us or fill out our online form to get a call back, and we’ll tell you everything you need to know about getting your IID installed. We’ll get you back on the road quickly, so you can put your DUI behind you and start moving on with your life.
Get a quick and easy IID installation with Smart Start! Get started today!
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