You know that if you're convicted of drunk driving, you may be expected to have an ignition interlock device (IID) installed into your vehicle. If you have one, you know you have to use it before you can drive.
What most people don't talk about is what happens if you fail the IID's test. There are many reasons that you might fail an IID, including using alcohol-based mouthwashes or having alcohol in your system from drinking the night before. When you fail the test, your vehicle will not start -- it's as simple as that.
You won't be able to drive again until you wait out the lock-out period. That could be as little as five minutes or as much as 24 hours. For example, if you blow and fail the test, the first failure might result in a five-minute lock out. If you fail again, you might be locked out for an hour. This continues until you are safe to drive.
There is a second test you have to take as well. It's a rolling re-test, which is given while you're driving. If you fail while driving, you're required to pull over and shut off the ignition. If you fail that test, you need to take the IID to a service center to have it reset, because it will go into Early Service Recall Mode.
Overall, nothing will end up happening if you fail your test, but it will keep you off the roads. If you have concerns about the IID not working correctly, you should report it to the service center and potentially your attorney.
Source: LifeSafer, "What Really Happens If I Fail My Ignition Interlock Breath Test?," Charles Hickman, accessed July 11, 2017