How Accurate Is an Ignition Interlock Test?

If you or a loved one needs to get an ignition interlock device (IID) installed, you may be wondering “how accurate is an ignition interlock test?” The answer is, VERY accurate. Every ignition interlock device installed in the United States must meet a set of stringent requirements. After all, the idea is to keep people from driving drunk. In order to do so, the devices need to be highly accurate, every time.

Most ignition interlock devices use what is known as an alcohol fuel cell sensor to ensure accuracy. 

NHTSA Specifications for Ignition Interlock Devices

The National Highway Transportation Safety Administration (NHTSA) has set out model specifications for ignition interlock devices to test IIDs for conformance and accuracy. All 50 states and Washington DC use these specifications in determining which IID manufacturers are allowed to operate in their states. Some of the main issues regarding accuracy include:

Ignition Interlock Sensor Technology

The NHTSA chose not to require the use of alcohol fuel cell sensor technology, as long as an IID met performance requirements. Most industry leaders, including ALCOLOCK, use fuel cell sensor technology, because it is the most accurate technology available.

Ignition Interlock Calibration Stability

The NHTSA specifications require an IID to maintain calibration stability for a minimum of 37 days (a 30 day service period + a seven-day countdown to lockout period). However, most IIDs available from reputable manufacturers will maintain calibration stability for much longer than that. This means that your service visits and the need for calibration can be decoupled. While many states require service visits every 30 days to download information the device has recorded and to check calibration stability, the fact is that your device will likely not need to be recalibrated at each service visit.

Ignition Interlock Precision

The most recent model specifications require IIDs to undergo testing showing they “experience no ignition locks in 20 trials at 0.000 g/dL (grams of alcohol/210 liters of air); not more than one ignition lock in 20 trials at 0.008 g/dL; and not more than one ignition unlock in 20 trials at 0.032 g/dL. These performance requirements represented an increase from 90% to 95% compliance at the 0.008 and 0.032 levels and 100% at 0.000.”

Cigarette Smoke and Acetone

NHTSA also requires ignition interlock devices to undergo testing to ensure they will not lock a vehicle if the cigarette smoke or acetone are present. Devices with fuel sensor technology like ALCOLOCK’s have no problem passing these conformance tests, since substances other than alcohol have no effect.

Ignition interlock devices must undergo a number of other conformance tests to meet NHTSA specifications. If you want an accurate device, your best bet is to go with one with an alcohol fuel cell sensor technology.

ALCOLOCK Ignition Interlock Devices

ALCOLOCK now has three ignition interlock devices to choose from. Your state will likely limit your choice of device to one that meets their exact requirements. Some states require that your IID be camera-equipped, GPS-equipped, or both. All states mandate that any ignition interlock devices installed in their state meet or exceed the NHTSA model specifications we mentioned above. All ALCOLOCK ignition interlock devices use fuel cell sensor technology for utmost accuracy, and are NHTSA-compliant. So don’t think one device is less accurate than another, or that one device is easy to fool.

Avoiding an Accidental Test Failure

As previously stated, the ignition interlock test is highly accurate in detecting even the smallest amount of alcohol on your breath. If you don’t have enough alcohol on your breath to fail the test, you may still get a warning from the device. And that test result will be recorded, just like everything else.

So how could you have an accidental test failure? This is not a false positive, because there is no such thing. The device will detect alcohol, period. But you may not realize that some things you eat or drink, or some medications you take have alcohol in them. This is why we advise you to wait 10-15 minutes after eating or drinking anything before submitting a breath sample. It is also a good idea to swish your mouth out with water before taking the test.

Some items that contain alcohol that could lead to an accidental test failure include, but are not limited to:

  • Mouthwash and mouth sprays
  • Some energy drinks
  • Non-alcoholic beer
  • Cough syrup
  • Vanilla
  • And more

If you believe you failed a test, or got a warning due to something you ate or drank other than an alcoholic drink, you should notify your monitoring agency, as well as your service provider.

Schedule Your Ignition Interlock Device Installation

Scheduling your ignition interlock device installation with ALCOLOCK is simple. Just call the service location most convenient to your home or job to schedule your IID installation. You can also call ALCOLOCK at (866) 700-9300. When choosing a location, remember that where you have your installation done is where you will have your monthly service appointments.

Your installation appointment will take about an hour. During that time the technician will physically install the device in your vehicle, and train you how to use it. They will also go over what all of the lights,  sounds, and screen messages mean. Finally, they will schedule your first service visit. Each service visit should take about 20 minutes.

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