Wichita Bail Bonds Blog

Most ignition interlock devices will fail a test if your blood alcohol concentration (BAC) is 0.02% or higher. That means even a small amount of alcohol in your system can cause a failed test. The specific BAC limit can vary depending on state law, court orders, or probation conditions, but Kansas and most states use 0.02% as the standard failure threshold. This level is much lower than the legal driving limit of 0.08% because interlock programs are designed to enforce total sobriety while driving.

Understanding the Interlock BAC Limit

An ignition interlock device measures the alcohol level in your breath before your vehicle starts. If it detects alcohol above the allowed limit, the car will not start. The limit is intentionally low to ensure drivers are completely sober when operating a vehicle.

• Fail threshold – Usually 0.02% BAC.
• Warning range – Some devices show a warning between 0.01% and 0.019% BAC.
• Legal limit for driving – 0.08% BAC for adults, but interlock limits are stricter.
• Zero-tolerance enforcement – Drivers with interlocks are expected to have no alcohol in their system at all.

What Happens After a Failed Interlock Test

If the device records a failed breath test, it prevents the vehicle from starting and logs the result in its system. Repeated failed attempts can lead to serious consequences, especially if you’re under court or probation supervision.

• Immediate lockout – The vehicle will not start until a clean test is provided later.
• Report to authorities – The failure is sent to your monitoring agency, probation officer, or licensing department.
• Extended requirements – Failing tests can add more months to your interlock program.
• Possible penalties – You may face fines, license suspension, or even jail time for multiple violations.

Causes of False Positives

Sometimes interlock devices detect alcohol from non-beverage sources, which can trigger a fail even if you haven’t been drinking. To avoid this, it’s important to avoid using certain products before testing.

• Mouthwash or breath sprays containing alcohol.
• Fermented foods like kombucha or energy drinks.
• Cold medicine or cough syrup with alcohol content.
• Smoking or vaping right before blowing into the device.

Tips to Avoid Interlock Fails

Since interlocks are sensitive and precise, drivers must take extra care before testing. Simple actions can help prevent failed readings and potential violations.

• Wait at least 15 minutes after eating, drinking, or using mouthwash.
• Rinse your mouth with water before blowing into the device.
• Keep detailed notes of any medication or food that could affect readings.
• Never attempt to tamper with or bypass the interlock device.

An ignition interlock device usually fails at a BAC of 0.02% or higher. Even trace amounts of alcohol from drinks, medication, or mouthwash can trigger a violation. Staying completely alcohol-free is the only way to ensure you pass every test and complete your program without penalties.