Idaho Ignition Interlock Requirements: When You Need One and How It Works

When Idaho Requires an Ignition Interlock Device

An ignition interlock device (IID) — sometimes called a car breathalyzer — is a breath-test unit wired into your vehicle's ignition system. You blow into it before starting the car, and it prevents the engine from starting if it detects alcohol above a preset threshold.

Idaho requires interlock installation in two situations:

During a Restricted Driving Permit (RDP). If you're granted a restricted permit during an ALS or DUI court suspension, an approved interlock device must be installed on every vehicle you operate. For an ALS, the court can waive the interlock only by specifying the waiver and notifying ITD. If the vehicle doesn't have an interlock, you can't drive it under the permit.

As a court-ordered condition. A judge may order interlock installation as part of a DUI sentence, particularly for repeat offenders or high-BAC cases. The court sets the duration.

For an ALS, ITD states that the interlock requirement begins 10 days after the 90-day ALS concludes and lasts one year; an RDP during the ALS period also requires an IID. For a criminal DUI, the court may impose an IID and the court order controls its duration.

Installation and Compliance

You can't install the device yourself — it must be done by a state-approved vendor who files an installation certificate directly with ITD. The vendor handles both the physical installation and the electronic notification to the state database.

Once installed, the device requires regular calibration and service on the schedule set by the vendor and, if applicable, your court order. Ask the vendor how device logs are downloaded and where reports are sent.

You're responsible for maintaining the device in working condition. If it malfunctions, you must bring the vehicle to the vendor for repair immediately — you can't drive a vehicle with a non-functional interlock.

What It Costs

Interlock devices are leased, not purchased. Typical costs in Idaho:

• Installation: Varies by vendor
• Monthly lease and monitoring: $70-100 per month (typical range)
• Removal: Varies by vendor
• Calibration visits: Ask the vendor whether they are included or charged separately

Total cost depends on the vendor, service schedule, and how long the device is required. Get a written quote covering installation, monthly service, calibration, and removal; ask the vendor about payment plans.

Violations and Consequences

The interlock device logs everything. These events can trigger violations:

• Failed breath test (BAC above threshold) when attempting to start the vehicle
• Failed rolling retest — the device prompts random retests while you're driving; a failed retest triggers an alarm sequence
• Missed rolling retest — ignoring the retest prompt is treated the same as a failure
• Tampering or circumvention — attempting to bypass the device, having someone else blow into it, or disconnecting the wiring

A violation can result in revocation of your RDP, extension of the interlock requirement, or additional criminal charges. If your restricted permit is revoked for an interlock violation, your full suspension reactivates and you lose driving privileges entirely.

CDL Holders Cannot Use an Interlock to Keep Driving Commercially

Idaho law strictly prohibits restricted, hardship, or probationary commercial driving permits. If you hold a CDL and receive a DUI — whether in a commercial vehicle or your personal car — your commercial driving privileges are disqualified for a minimum of one year. An interlock device cannot be used to maintain commercial driving authorization during that period.

You may qualify for an RDP on your Class D (personal) license with an interlock, but you cannot operate any commercial motor vehicle until the disqualification period ends and you complete the full CDL reinstatement process.

Getting Through the Interlock Period

The interlock period is a hassle, but it ends. The key is avoiding violations that extend it. Follow the vendor's instructions for avoiding false positives, keep the device clean, and attend every calibration appointment on time.

The Idaho Driver's License Reinstatement Guide includes a compliance timeline for interlock requirements alongside the full RDP application process, so you know exactly when the interlock period starts, what triggers a violation, and when you can get the device removed.

See more Idaho guides →