Ignition Interlock Devices in Wisconsin: What You Need to Know

July 6, 2026

Ignition interlock device requirements in Wisconsin

If you've been charged with an OWI in Wisconsin, you may be required to install an ignition interlock device (IID) in your vehicle. This requirement has expanded significantly in recent years, and it affects more people than ever before.

What Is an Ignition Interlock Device?

An ignition interlock device is a breathalyzer that's installed in your vehicle and connected to the ignition system. Before you can start your car, you need to blow into the device. If it detects alcohol above a preset limit (typically .02%), the engine won't start. The device also requires "rolling retests" — random samples while you're driving — to make sure you haven't been drinking after starting the car.

Who Needs an IID in Wisconsin?

Wisconsin law requires ignition interlock devices for:

  • First-time OWI offenders with BAC of .15% or higher — 12-month requirement
  • All repeat OWI offenders — 12–36 months depending on the offense
  • Drivers who refused chemical testing — In some cases
  • Drivers with prior OWI-related convictions — Even if the current charge isn't OWI

As of 2023, Wisconsin law expanded IID requirements to include more first-time offenders. If your BAC was .08% or higher and you have certain aggravating factors, you may be required to install an IID even on a first offense.

How Much Does an IID Cost?

The costs add up quickly:

  • Installation fee: $75–$150 (one-time)
  • Monthly monitoring fee: $70–$150 per month
  • Removal fee: $50–$100 (at the end of the requirement period)
  • Total for 12 months: Approximately $1,000–$2,000

Some states offer reduced-cost programs for low-income drivers, but Wisconsin's program is limited. You're responsible for all costs unless you qualify for a specific waiver.

How Does the IID Work Day-to-Day?

Living with an IID takes some getting used to. Here's what to expect:

  • You'll blow into the device before starting the car (usually 5–10 seconds)
  • The device will request random rolling retests while driving (typically every 30–60 minutes)
  • If you fail a test, the car will honk and flash lights until you turn it off
  • You'll need to return to the monitoring center monthly for data download and calibration
  • You can't start the car if someone else has been drinking — even a passenger's alcohol can trigger a false positive if they blow into it

Can You Drive Someone Else's Car?

If you're required to have an IID, you're generally only allowed to drive vehicles that have an IID installed. Driving a car without an IID while you're under an IID requirement can result in additional penalties. Some people install IIDs on all household vehicles, while others limit themselves to one vehicle with the device.

What Happens If You Violate the IID Requirements?

Violations — like failing a test, missing a rolling retest, or tampering with the device — are reported to the DMV and the court. Consequences can include:

  • Extension of the IID requirement period
  • Additional license suspension
  • Contempt of court charges
  • Revocation of driving privileges

Can an Attorney Help You Avoid an IID?

In some cases, yes. An experienced DUI attorney may be able to negotiate a plea agreement that avoids the IID requirement, or reduce your BAC level below the .15% threshold. This is one of many reasons why having legal representation matters.

Call us at (608) 535-6554 for a free consultation.