Can Ignition Interlock Devices Give False Readings?

March 21, 2019

If you have been court-ordered to install a car breathalyzer as the result of a DUI offense, you may be unsure as to how the device works. To that end, you may even, wonder, “Is it possible for my ignition interlock device to give false readings?” To answer this question, we need to break down how blood alcohol content is measured and whether or not there is room for potential errors.

Measuring BAC

The simplest and most effective method for field testing a person’s blood alcohol content is by measuring a breath sample. Breathalyzers have been used for breath alcohol testing since the 1960s. Over the sixty years they have been in use to test BAC levels, various updates and improvements have been made on the device concept to:

  • Improve accuracy
  • Decrease false positive readings
  • Maintain calibration
  • Increase the speed of results

Interlock devices are quasi breathalyzers/immobilizers connected to the vehicle’s ignition system. If you want to start the car, you must blow into the interlock device and pass a breath test, which proves that you are sober and safe for the road.

Potential Error Sources

There are a handful of potential causes behind a false reading. They include:

  • Compounds with methyl groupsBreathalyzers detect alcohol on any compound that contains a methyl group in its structure. While this is fine for testing alcohol, there are many everyday products that contain trace amounts of alcohol in them. This is why mouthwash is the most common cause of a false reading. Other causes include:
    • Air freshenersBreath mints
    • Breath sprays
    • Cleaning fluids
    • Colognes
    • Coolant fluid
    • Dark chocolate
    • Dentyne
    • Glue paint
    • Gummy bears
    • Hand sanitizer
    • Inhalers
    • Mints
    • Paint removers
    • Perfumes
    • Radiator fluid
    • Windshield wiper fluid
  • Cigarette smokers – Long-term cigarette smokers are more prone to an incorrectly high BAC than people who do not smoke. Smoking large amounts of tobacco increases the natural production of acetaldehyde, which can be falsely detected as alcohol.  
  • A Bad Sample – Some devices require a specific breathing pattern or a minimum breath sample. If you give a poor sample or incorrectly exhale, that could result in a faulty breath sample.
  • Natural Alcohol Production – All humans naturally produce ethanol in their bodies. This production is known as endogenous, which means internally generated. While this occurs throughout the body, the intestines typically have the highest concentration of bacteria that produce alcohol. If you consume a lot of carbs, you could have elevated levels of endogenous alcohol production. Some people even have “auto-brewery syndrome” where their internal alcohol production is so high that it causes them to become intoxicated without drinking anything.
  • Imprecise Readings – There is an inherent margin of error in any breath BAC analysis. Any result is typically construed as the BAC adds or minuses .01%. So, a BAC reading of .07 could range from .06 to .08.

LowCost Interlock

Low Cost Interlock has worked to ensure that their devices produce the most accurate results. To improve accuracy, LCI has simplified the process required for giving a breath sample. You do not need to perform a certain combination of blowing, sucking, or humming; all you have to do is breathe out. Additionally, LCI requires that you recalibrate your interlock device periodically in order to maintain accurate readings.

While any device that uses a breathalyzer can be suspect to false readings, LCI has made it their goal to render these results an anomaly. Few things can be more frustrating than receiving a violation when you were innocent. LCI takes this to heart, so if you have any questions about false readings or if you’ve received an incorrect interlock device violation, contact a Low Cost Interlock representative today!

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