My Ignition Interlock Requires a Test While Driving – Is that Dangerous?

If you’re unfamiliar with ignition interlock devices — those car breathalyzers that prevent a vehicle from starting if the driver has been drinking — you might think that they’re easy to bypass. “Just have a friend blow into it,” people say. “Or start the car while you’re sober, and then leave the motor running while you’re at the bar drinking. What could be easier?”

In fact, interlock manufacturers have developed technologies that make it very difficult, Lifesafer ignition interlock rolling re-testif not impossible, to bypass an ignition interlock and drive drunk.

One such technology is the rolling retest. After you have passed the initial test and have been driving a few minutes, the device will require you to blow into it again.  If you fail or refuse this rolling re-test, alarms will sound — the horn will honk and lights flash, forcing you to pull over. This re-test is required periodically in order to prevent scenarios like the one described above. “Curb service” — having a sober friend “assist” you by blowing into the interlock — is no longer feasible.

Sometimes drivers are concerned that the rolling re-test is dangerous or distracting. In fact, it’s perfectly safe when done correctly.

When your interlock signals for a re-test, you have a certain number of minutes to pull over to a curb or shoulder and blow into the device.

If pulling over is not possible, you can still take the test while driving — it’s not distracting at all. On a well-designed ignition interlock, the rolling re-test uses audio only. The interlock emits a tone to signal that you should blow into the device. A different tone signifies that you have passed the test. There is never a need to take your eyes off the road.

Not only is a re-test not dangerous, it’s one of the most important safety devices on your car. It ensures that you can keep on driving, in compliance with the law, unimpaired and safe from harm.