Wisconsin Ignition Interlock — Requirements & Costs

An ignition interlock device (IID) is a breathalyzer wired into your vehicle's ignition system. It prevents the engine from starting if it detects alcohol on your breath above a preset threshold §343.301. In Wisconsin, IID requirements are a central part of OWI consequences.

required for a first offense only if the person refused testing, had an alcohol concentration of 0.15 or more, or had one or more prior convictions; not required for a routine first offense under 0.15 with no priors.

not less than 1 year, nor more than the maximum operating privilege revocation period for the refusal or violation, as ordered by the court.

Common violations that can extend the IID period or trigger additional consequences:

• Failed startup tests (BAC above threshold)
• Failed rolling retests
• Missed calibration appointments
• Tampering with or attempting to circumvent the device
• Operating a vehicle without an IID when one is required

IID costs are borne by the offender and include:

• Installation fee
• Monthly monitoring/rental fee
• Removal fee
• Calibration fees (may be included in monthly rental or charged separately)

While the IID is a restriction, it is also the mechanism that allows many offenders to resume driving sooner than they would under a full suspension. In Wisconsin, Occupational license available with IID during OWI suspension; applies after 30-day hard suspension for first offense. Complying fully with IID requirements — no violations, on-time calibration — is the fastest path to full reinstatement.