What is an ignition interlock device?

All about ignition interlock devices


An ignition interlock device, or IID, is a small device that connects into the ignition of a DUI offender’s vehicle that measures a user’s breath alcohol concentration (BrAC). An IID prevents a vehicle’s engine from starting until the user has provided a breath sample that is below the legal limit set by your state. If the driver’s breath sample is above the state limit, the vehicle will not start. Drivers with an IID must periodically provide breath samples throughout each trip to verify the absence of alcohol. Additionally, ignition interlock devices track the user’s activity and provides a record of any violations to your state’s monitoring department.


Who is required to get an IID?

An ignition interlock device is most commonly required of DUI offenders, though there are many scenarios in which an ignition interlock device may be ordered:

  • Court-Ordered IID Restriction
  • DMV-Ordered IID Restriction
  • Shortened Driver License Suspension or Revocation (Optional DMV IID)

You must have an ignition interlock device installed if you are trying to obtain the following:

  • Reinstatement of your driving privilege
  • Issuance of a Limited Driving Privilege (LDP)
  • Issuance of a Restricted Driving Privilege (RDP) - Points (Alcohol)
  • Issuance of a Restricted Driving Privilege (RDP) - Alcohol


How is an ignition interlock device different from other breathalyzers?

Both ignition interlock devices and breathalyzers measure a user’s BrAC. However, an IID is connected to a vehicle’s ignition and must be used in order to start a vehicle’s engine. 


How do I install an interlock device?

Drivers who require an IID can have the device installed by a certified vendor. The vendor will then supply the state with proof of installation. To find a list of vendors for your state, contact your local DMV, probation department or court. You can also lease your ignition interlock device through a number of online vendors:

  • Intoxalock
  • AlcoTest Inc
  • Simple Interlock
  • LifeSafer
  • Alcohol Detection Systems
  • CAM Systems
  • 1A Smart Start
  • Guardian Interlock Systems


How much does an ignition interlock device cost?

A DUI offender must pay all costs associated with an IID, including installation, monitoring and calibration. The cost of an interlock device will depend on the state you live in, as well as a variety of factors: 

  • Any additional required features, such as a camera or GPS
  • The length of time you are required to have an ignition interlock device installed
  • The year, make, and model of your vehicle

Cost estimate for an IID:

  • $70 to $150 for installation
  • $60 to $80 per month for device monitoring and calibration

Many states offer financial assistance for IIDs for users that meet certain qualifications. Companies like Intoxalock offer options for payment and work with you on leases.


What accessories come with a car breathalyzer? 

In some states, a camera and a GPS feature may be required with your ignition interlock device. These car breathalyzer accessories are usually court-ordered. 


What’s a random retest? 

A random retest occurs when a user is randomly prompted to retake the IID breath test. If the user fails a retest, meaning the random IID test detects a BrAC above the state’s designated limit, a violation will be recorded on the ignition interlock device and the offender’s suspension may be extended. However, for safety purposes, a failed random retest will not result in the car’s engine being shut off.


What is considered a violation of an IID?

The following are considered an ignition interlock device violation and may result in a fine or a suspension extension:

  • Device tampering
  • Circumvention
  • Confirmed breath alcohol level above your state’s legal limit


When and how do I remove an ignition interlock device?

Each state mandates a required period of time that an IID must be installed. Generally, an ignition interlock device can be removed from an offender’s vehicle with permission from the State if he or she has not done any of the following throughout that time period:

  • Tried to start the vehicle with a breath alcohol content over the state’s designated limit
  • Failed to take or pass any required retest
  • Failed to get scheduled maintenance, repairs, calibration, monitoring, inspection or replacement of the device

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