Ignition Interlock Device (IID): Requirements, Cost, and How It Works

An ignition interlock device is a small breathalyzer unit hardwired into your vehicle's ignition system. It is installed by an authorized service provider (such as Intoxalock, Smart Start, LifeSafer, or Low Cost Interlock) at one of their service centers. The installation takes about an hour and does not permanently alter your vehicle.

To start your car, you must blow into a mouthpiece attached to the device. The IID analyzes your breath for alcohol content. If your breath alcohol concentration (BrAC) is below the preset limit (typically 0.02% to 0.04%, which is well below the legal driving limit of 0.08%), the car starts normally. If it detects alcohol above the limit, the engine will not start, and a lockout period begins -- usually 5 to 30 minutes before you can try again.

While driving, the IID will prompt you for rolling retests at random intervals (typically every 15-45 minutes). You have a few minutes to provide a breath sample. If you fail a rolling retest or do not provide a sample, the device does not shut off the engine (that would be dangerous), but it logs the violation and may trigger your horn and lights to flash until you pull over and turn off the engine.

Failed startup test: The car will not start. You must wait through a lockout period (5-30 minutes) before trying again. The failure is logged and reported to your monitoring authority at your next calibration appointment (or in real-time if your device has cellular reporting).

Failed rolling retest: The car continues running (for safety), but the device logs a violation, and your horn may honk and lights flash. You should pull over safely and turn off the engine. The violation is reported to your monitoring authority.

Multiple failures: Repeated failures or violations can trigger an early lockout (the device locks you out for an extended period, often requiring a service center visit to reset) and may result in your court or probation officer extending your IID requirement, revoking your restricted license, or imposing additional penalties.

Important: Mouthwash, breath sprays, certain foods, and some medications can trigger a false positive. Wait 15 minutes after eating, drinking (anything, including water), or using mouthwash before blowing into the device. If you get a false positive, rinse your mouth with water, wait a few minutes, and try again.

IID devices are designed to detect and report tampering attempts. Modern devices include cameras that photograph the person providing the breath sample (to prevent someone else from blowing for you), sensors that detect unusual breath patterns, anti-circumvention technology that detects attempts to disconnect or bypass the device, and tamper-evident seals on the wiring.

Attempting to tamper with, disable, or circumvent an IID is a separate criminal offense in every state that requires them. Penalties include fines ($1,000+), additional jail time, extended IID requirement (often doubled), license revocation, and new criminal charges.

Having someone else blow into the device for you is also a crime -- for both you and the person helping. Some states charge this as a felony. The camera on modern IID units makes this easy to detect.

Driving a different vehicle without an IID while your IID requirement is active is also a violation that can result in additional criminal charges and extended restrictions.

In most states, you can choose your IID provider from a list of state-approved vendors. Major providers include Intoxalock (nationwide, one of the largest), Smart Start (nationwide, competitive pricing), LifeSafer (nationwide, known for customer service), and Low Cost Interlock (available in many states, emphasizes affordability).

When choosing a provider, compare installation fees (range: $70-$150), monthly lease and monitoring costs (range: $60-$150), calibration fees and frequency (every 30, 60, or 90 days), service center locations (convenience matters since you will visit regularly), customer service reputation (read reviews), and any hidden fees (lockout reset fees, violation fees, early termination fees).

Some states set maximum prices that IID providers can charge, while others allow market pricing. Your attorney, probation officer, or state DMV can provide a list of approved providers in your state. Some providers offer income-based discounts or payment plans.

When your IID requirement period ends, you must go through a formal removal process. Do not simply disconnect the device yourself -- this could be reported as tampering.

Steps to remove your IID: Verify with your court, probation officer, or DMV that your IID period has been completed. Some jurisdictions require a court order for removal. Obtain a compliance report from your IID provider showing you met all requirements. Schedule a removal appointment at your provider's service center. The provider removes the device and restores your vehicle's ignition to its original configuration. The provider sends a compliance certificate to the state confirming the device was properly removed.

Removal typically costs $50-$100. The appointment takes about 30 minutes. Make sure you have confirmation from the monitoring authority that your requirement is complete before scheduling removal -- removing the device before your period ends is a violation.

Plan extra time for your morning routine. The breath test adds 30-60 seconds to starting your car. In cold weather, the device may take longer to warm up.

Avoid alcohol completely. Even small amounts from the previous night can trigger the device. The IID preset limit (0.02-0.04%) is much lower than the legal driving limit (0.08%). One drink the night before can still register the next morning.

Watch what you eat and use. Mouthwash containing alcohol, breath sprays, fermented foods, energy drinks, and even some medications can cause false positives. Wait 15 minutes after consuming anything before testing.

Keep your calibration appointments. Missing a calibration is reported as a violation. Most states require calibration every 30-90 days. Set calendar reminders.

Tell passengers in advance. The rolling retest will happen while driving, and the device will beep. Let passengers know so they are not startled. You can pull over safely to provide the retest sample.

Keep the mouthpiece clean and store spare mouthpieces in the car. Dirty mouthpieces can cause inaccurate readings.