Can an Ignition Interlock Device Shut My Vehicle Off?

A lot of people ask us “Can an ignition interlock device shut my vehicle off?” In fact, it’s such a common question we figured we should address it on our FAQs page. The short answer is NO. While your ignition interlock device (IID) can and will prevent you from starting your car if it detects alcohol on your breath, the IID will not, and cannot, shut down your engine while you are at a standstill, or while you are in motion. That would be an extreme safety issue and would violate the National Highway Transportation Safety Administration (NHTSA) model specifications for ignition interlock devices.

How an Ignition Interlock Device Works

An ignition interlock device consists of two main parts — a control box called an Electronic Control Unit (ECU) which is hooked into your vehicle’s starter, and the handheld unit, where you blow into the device. Every time you give a breath sample, the handheld device communicates to the ECU. The IID uses an alcohol fuel sensor to detect even the smallest amount of alcohol on your breath. Most states set the lock-out level at .002 or .025 BAC.

You are required to blow into the device every time you want to start your vehicle. If you pass the test (no detectable alcohol) you can start the car as you normally would. If you fail the test (alcohol detected), you fail the test, and the device locks you out, preventing you from starting your car. Depending on your state’s requirements, there will be a set amount of time before you can give another breath sample. Each state determines how many failed tests you can have before you are permanently locked out and have to have your vehicle towed to a service center.

Rolling Retests

In addition to the initial breath test to start your vehicle, you are required to give random breath samples as you are driving. These are called rolling retests. The device will alert you a few minutes before you are to submit the breath test, so you can do it safely. We recommend you pull over or park before submitting the breath test, but many people give the breath sample while they are actively driving. If you fail the test, the ignition interlock device WILL NOT SHUT YOUR VEHICLE OFF. But be advised, the device will record the test failure.

The device records everything, and each month, or every 60 days depending on your specific case, you will take your vehicle into the service center so the technician can retrieve the data record, and send it on to your monitoring agency. The device records:

  • The time and date of every test you take
  • Your location if the device is GPS equipped
  • Your picture each time you take the test, if your device is camera-equipped
  • Whether you passed or failed the test
  • If you skipped a rolling retest
  • If you kept driving after failing a rolling retest
  • If you tried to circumvent or tamper with the device

If you fail a retest and you intentionally or accidentally shut off the engine, it will not restart without a service call. This is a requirement of the NHTSA.

Find an Ignition Interlock Device Installation Location Near You

ALCOLOCK has multiple ignition interlock device installation locations in states throughout the country, and we’re always adding new locations. To schedule your ignition interlock device installation, you can call the service center nearest you directly, or you can call us at 866-700-9300. For general questions, or to schedule online, you can also use our contact form, and someone will get back to you shortly.

What to Expect at Your IID Installation

First off, you’ll want to make sure you have someone drive you and your vehicle to the ALCOLOCK service center. You’ll be able to drive the vehicle once the IID is installed. You can expect your ignition interlock device installation appointment to last about an hour. Your service technician will install the ECU and calibrate the handheld device to you, specifically. If someone else will be driving your vehicle while it is equipped with the IID, bring them with you to the installation appointment so they can receive training, too. Before you leave, you’ll sign some paperwork and receive an owner’s manual.

You will also schedule your first service appointment. And don’t worry — the device will give you reminders as that date approaches. Lastly, if you have any questions or issues with your ignition interlock device, you can call us 24/7 at 866-700-9300. You may also want to visit our Support page for troubleshooting tips for ALCOLOCK ignition interlock devices.

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