How Do Ignition Interlock Devices Detect Breath Alcohol?

If you have been ordered to install one in your vehicle, you might be interested in the science behind how ignition interlock devices detect breath alcohol. To understand how they work, you need to understand how the human body processes alcohol.

The Human Body and Alcohol

When you have a beer, glass of wine or mixed drink, the alcohol you drink flows almost immediately through your body’s membranes and enters your bloodstream. Of course your bloodstream then carries the alcohol to every part of your body, including your heart, lungs, liver, stomach and intestines.

When your heart pumps alcohol-infused blood to your lungs, you actually breathe out a little bit of alcohol every time you exhale, and your breath smells of alcohol. So rinsing your mouth out with water or having a cup of coffee to mask the smell won’t fool the ignition interlock device, because it is testing your breath from your lungs.

How Breathalyzers Work

When you use the interlock device, you blow into the mouthpiece on your handheld device, and the device registers your breath alcohol content (BAC), and communicates that to the Electrical Control Unit (ECU) that is connected to your vehicle’s starter. .

Ignition interlock devices like the ones from ALCOLOCK use what’s called an ethanol fuel cell sensor. Fuel cell sensors utilize an electrochemical process in which any alcohol on your breath reacts with a catalytic electrode to produce an electric current. The breathalyzer measures that current to determine your BAC. The more alcohol on your breath, the higher the BAC level. If your BAC is above the set limits for your state’s program, the ignition interlock device will not let you start your vehicle. It will record the test failure, and those results will eventually be sent to the person or agency monitoring your progress, such as the DMV or your probation officer.

Each state has different requirements, but if you fail the test a certain number of times in a row, you may be locked out for up to 24 hours. At the time of your interlock device installation, your technician will go over how to use the device, and what your program requirements are. Our goal is to help you be compliant with your program so you can get your life back to normal.

How Long Ignition Interlock Devices Detect Alcohol

Remember that alcohol is strong stuff. A cold shower and coffee aren’t enough to get alcohol out of your system. Only time will get alcohol out of your system. If you were drinking heavily the night before and didn’t roll in until around 1 a.m., if you’re headed to work at 8 a.m., you may fail the breath test when you go to start your car.

Here’s why. It can take several hours for your body to metabolize alcohol, depending on how much you’ve had to drink, what you had to drink (liquor, beer, wine), whether you had anything to eat, and many other factors. So if you were out partying the night before, consider taking public transportation to work in the morning, or calling an Uber.

I Haven’t Had Any Alcoholic Drinks, But I Failed the Test

So we did say ignition interlock devices are highly sensitive to alcohol. Even if you haven’t consumed an alcoholic beverage, there may still be alcohol on your breath. There are a number of everyday things that contain enough alcohol to cause you to fail a breath test, including:

  • Mouthwash
  • Breath spray
  • Vanilla (think baked goods)
  • Energy drinks
  • Foods with alcohol in the recipe (Pasta with Vodka sauce or rum cake)

Your best option is not to use or eat these products while you are in the interlock device program. If you believe that you failed the breath test even though you hadn’t been drinking, you should inform your DUI lawyer and other officials involved in your program.

Ignition Interlock Devices and Maintenance Visits

By law, you are required to have your technician check your device monthly, and recalibrate the device as necessary. For your convenience, your device will send you appointment reminders. If you miss a monthly service appointment, call us ASAP to reschedule. If you go 5-7 days past your appointment without coming in for service, your ignition interlock device will enter lockout mode. The only way to get back on the road if that happens is to have to have your vehicle towed to a service center for the maintenance visit.

ALCOLOCK With You On the Way Back

At ALCOLOCK, your success is our goal. We’re dedicated to helping you comply with the terms of your DUI/DWI ignition interlock device program. We make it easy for you to work your way back to full driving privileges. Call us at 866-700-9300 with questions, or use our contact form to schedule an installation.