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Ignition Interlock Device (IID) FAQs

The most common questions about ignition interlock devices and car breathalyzers, answered. If your question is not listed, contact us at (877) 275-3974 and we can help.

 Frequently Asked Questions and Answers

What is an ignition interlock device?

An ignition interlock device, or car breathalyzer, is a small alcohol monitoring device that is wired into a vehicle’s ignition system to prevent drunk driving. The device requires the driver to take a breath alcohol content, or BrAC, test before they can start the car. To do so, the driver provides a breath sample using the device, which then measures the alcohol content. 

Each state is responsible for setting the legal limit for these BrAC tests, which is different from the legal threshold for DUI. While a DUI threshold is typically .08 percent (except in Utah where it’s .05 percent), for a BrAC sample the limit is much lower. If the driver’s breath sample is measured above the lower set limit, the vehicle will not start. 

Throughout most trips, the interlock device will request random retests to ensure the driver stays sober and prevent tampering. The interlock device also tracks the user’s activity. Violations and tampering attempts are also recorded and provided to the monitoring authority in the relevant state.

What are the best ignition interlock device companies and devices?

We’ve done the research so you don’t have to. 

We took into account cost, convenience, device reliability, state certification, suspension history, ratings, and customer reviews when researching. You can read our in-depth findings as you explore different providers. We hope it will guide you in your decision.

What are the steps I need to follow before installing an interlock device?

The most important thing you will need to verify is that you have court approval to install your device, if it is mandated by the court. This will ensure you follow policy and get credit for your installation. Get your paperwork in order and verify that your chosen provider is approved, and make your appointment. 

What is a volunteer ignition interlock device?

Some IID users do not install because they were required by the court. Instead, some customers choose to install it as an aid, ensuring sober driving, or to protect their teen drivers from driving drunk. Anyone can have a device installed at any time, if they wish to.

Will I have to get an interlock device?

This depends on the circumstances of your offense, and your state law. A state specialist can help with specific questions. It should be made clear during your court proceedings that an interlock will be required as well.

Who are certified providers in my state?

We’ve researched state policies for you. Check your state’s page to see approved providers. Additionally, your attorney or the court should be able to tell you who these approved providers are.

Cost & Pricing

How much does an ignition interlock device (IID) cost?

This will depend on the provider and potentially your state’s requirements. In some states, multiple models are accepted while others offer a single model. 

Whether the device is mandated or voluntary, users are responsible for paying all costs. This includes installation, calibration, and any associated fees. Typically, the devices cost between $70 and $150 for installation, and the monthly lease price is between $40 and $100. Intoxalock advertises prices between $2.50 and $3.50 per day for their devices, as do some of their competitors. 

How to Install an Ignition Interlock Device

How does an ignition interlock device connect to my car? How does it work?

You will need to visit a certified technician to have your ignition interlock device installed. They have been professionally trained and know how to install the device without interfering with your vehicle. Since the device is wired directly into your vehicle’s ignition system, it’s not a good idea to attempt to install, tamper with, or repair the device yourself. Also, when you have the device installed, you will need to notify your IID provider when having maintenance performed. 

Once installed, the IID or car breathalyzer will require the user to blow into the mouthpiece attached to the device. The device will measure the driver’s Breath Alcohol Content and allow them to start the vehicle once they pass. Until a passing breath sample is provided, the car cannot be started.

How long do you have to have an interlock device?

This is typically mandated by the court or statute in your state. The National Conference of State Legislators says that most first offenders are usually required to have an interlock device for a year after the end of the license suspension or revocation period. Repeat offenders may have lengthier terms.

Additionally, some states are compliance-based, meaning that violations of the interlock policy could result in an extension of the interlock term. Check your state’s interlock policies to see if your state is compliance-based.

Who installs an interlock device?

All state-approved providers are required to have certified technicians install their devices. A certification ignition interlock installer would thus be required to handle and set up your interlock device. Some providers have proprietary shops to complete this work, and others train technicians in independent shops to complete the installation and calibration for their IIDs. 

Please note that proper installation is not just a preference, it is the law. Laws are in place that explicitly do not permit the participant to handle their own equipment during the installation or de-installation process. 

How long does an ignition interlock device installation take?

With an appointment, the installation process should take approximately one hour. The specific shop you are visiting should be able to give you a better timeline, as it can take longer depending on what type of vehicle you need to have the device installed in.

Will an ignition interlock device damage or hurt my vehicle?

No, an ignition interlock device will not harm your vehicle if it is properly installed. That’s why it is important to go to a certified technician for your installation. Companies like Intoxalock partner with installation locations across the country who are experts in working with a vehicle's electrical system. Interlock providers also employ in-house experts who continuously test devices and work with new vehicles to ensure the devices can be safely installed in newer cars.

Can an ignition interlock be installed on a motorcycle?

Currently, most companies do not install interlock devices on motorcycles. This is because of the potential safety issues involved. 

How do I schedule my ignition interlock installation?

After selecting your provider, find the specific location you want to visit. You should be able to schedule online or with a phone call, via the interlock provider. Since interlock providers work with the local installation centers, they can help customers schedule an appointment with a location that is available, trained to install on the make and model of the customer’s vehicle, and the right price and distance away from the customer’s location.


What type of insurance do I need and what does it cover?

It should be made clear at sentencing if you will need to obtain high-risk insurance. It’s extremely common to have this requirement for special high-risk auto insurance following an alcohol-related traffic offense. This type of insurance is often called SR-22, or FR-44 in some states. An SR-22 is a Certificate of Financial Responsibility that verifies you have liability coverage included in your car insurance. In many cases, obtaining SR-22 insurance is a requirement for getting a limited license or restricted license.

How do I obtain an SR-22?

You can find SR-22 insurance coverage either through your current provider if they offer it, or an insurance company that provides a la carte SR-22 coverage. When you obtain the coverage, you will have to file the form with your state’s DMV. Not all providers offer this type of high-risk insurance, so you may need to search to find a provider.  

How much does an SR-22 cost?

The cost will vary depending on a number of factors, including the specifics of your offense, the car you drive, and your previous driving record. An SR-22 requirement will likely put you into the high-risk driver category, which will cause your premiums to increase throughout the duration of the requirement. If you have an SR-22 requirement, your car insurance company will likely classify you as a high-risk driver. In addition to the cost of the coverage, the filing fee for the SR-22 or FR-44 is typically between $25 and $50. We have more information on SR-22 providers here.


What is a BAIID?

BAIID, or Breath Alcohol Ignition Interlock Device, is another term for ignition interlock device or car breathalyzer. Some states use this term, but it is still describing a device installed in a vehicle that measures a driver’s breath alcohol content (BrAC). To start their vehicle, users must provide the BAIID with a sample breath that is negative for alcohol. Some states require BAIID devices to be equipped with a camera that captures the driver’s image as he or she completes the breath test. While they can be obtained by anyone for voluntary purposes, in many cases they are required for DUI offenders after conviction.

Ignition Interlock Device Statistics

How do ignition interlocks and breathalyzers save lives?

Ignition interlock devices save lives because they prevent drivers from starting their vehicles while drunk. It also allows offenders to attend meetings, keep their job, and maintain their driving privileges while also staying safe.  

Recently, Mothers Against Drunk Driving (MADD) released a report in support of mandatory interlock requirements for all offenders. The report stated that: 

  • Interlocks prevented 3.78 million attempts to drive drunk between 2006 and 2020.
  • The Insurance Institute for Auto and Highway Safety reported that mandatory laws for all DUI offenders reduce deaths by 16 percent (2018)
  • In 2006, MADD started lobbying for mandatory interlock requirements. At the time, New Mexico was the only state to have one. Now, 34 states have mandatory IID requirements.