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BACtrack S75 Pro Operating Instructions

Below are basic operation guidelines for the BACtrack S75 Pro Breathalyzer. For more detailed instructions and explanations, please read the BACtrack S75 Pro Breathalyzer Owner’s Manual.


IMPORTANT: Users must wait 20 minutes after eating, drinking, or smoking before blowing into the S75 Pro Breathalyzer. Failure to wait 20 minutes can provide inaccurate test results and may damage the sensor.

    • Step 1

      Insert a mouthpiece into the slot. The side with the wider diameter slides into the slot first. It is recommended to insert a fresh mouthpiece before each test.

    • Step 2

      Press the Start button. The S75 Pro will quickly display the total number of tests performed, and then begin a countdown.

    • Step 3

      When the countdown approaches 2, begin to inhale a deep breath.

    • Step 4

      When the countdown reaches zero, "START" will flash and the screen will display three lines. Blow through the mouthpiece firmly and continuously for five seconds or until there is a double beep sound.

    • Step 5

      Once the sensor has analyzed the breath sample, the estimated BAC value is displayed.

The displayed result is an estimate of the test subject’s BAC.

A breath alcohol tester cannot determine the exact BAC in the blood of the test subject. Correlation between Breath Alcohol Content and Blood Alcohol Content depends on many factors, such as temperature and health conditions. Therefore, only use this device as a tool to screen for the presence of alcohol.
Many people consider a 0.02% or greater a positive test for alcohol in “zero tolerance” screening. Most states have 0.08% as the legal BAC limit for tasks such as operating a motor vehicle. Some states prohibit driving commercial vehicles or any vessel with a 0.04% BAC or higher. Many states and countries prosecute individuals for driving under the influence at any level.

Powering Off

To turn the power off at any time, leave the unit alone. Not touching the Start button for 30 seconds will trigger it to automatically shut itself off with minimal effect on the life of the battery.

Error Notifications

      • If a user does not blow a sufficient breath sample, the LCD will display “FLO.” Press Start to restart the countdown cycle and retest. Be sure to blow firmly and continuously for five full seconds while testing. 

      • If there is no breath sample blown within 15 seconds, the LCD will display “Out.” Press Start to restart the countdown cycle and retest.

      • If the unit is powered on outside of the acceptable temperature range (0-40 °C or 32-104 °F), this image will display and testing cannot be performed.

      •  If the battery indicator display is empty, install two new alkaline AA batteries.

Advanced Menu Options

To adjust the Advanced Menu Options you must press and hold the Mode button for five seconds while the unit is performing its initial countdown. This is the only time you can enter this menu. Once you do so, you can cycle through the menu options below by tapping the Mode button.


      • Breathalyzer screen 1Units of Measure - By default, the BACtrack will display test results in %BAC, which is the standard in North America and in many other regions. To change to a different unit of measure, press the Start button. You can select Promille (0/00) or mg/L as alternate units of measure.
      • Audible Warnings - By default, the BACtrack S75 Pro does not sound an audible warning after a specific %BAC result. To set an audible warning at or above a specific %BAC threshold, press Start button to cycle through %BAC values.
      • Blow Time - The S75 Pro defaults to the longest blow time available with the unit, which is five seconds. This provides a deep lung air sample and the most accurate test result. To select a shorter blow time, press Start.  
      • Flow Detection Settings -  Use this option to adjust how hard a user is required to blow. Press Start to toggle the settings between HI (requiring a more forceful breath), LOW (requiring a gentler breath) and USER. When testing in USER mode, the operator must press Start during a breath sample to activate the pump and perform a test.