How Alcohol Interlock Devices Work 

Before the engine can start, the driver must provide a breath sample into the device. The system measures the alcohol level in the breath, and if it is below the permitted limit, the vehicle will start. If alcohol is detected above the limit, the engine will remain immobilised.

To ensure ongoing compliance, the device will prompt the driver to provide additional breath samples at random intervals. These rolling retests confirm that the driver remains alcohol-free whilst on their journey. Pulling over to perform the retest is strongly recommended, but if traffic conditions do not permit pulling over, a retest may be performed whilst driving.

Many interlock systems include a camera that captures an image during each breath test. This helps confirm that the correct person is providing the sample and prevents others from attempting to bypass the system on behalf of the driver.

If alcohol is detected during a pre-start test, the vehicle will not start. If alcohol is detected during a rolling retest, the device may trigger warnings such as alarms or lights until the vehicle is safely stopped. All failed tests are recorded and may impact your compliance with the program.

Every interaction with the interlock device is recorded, including breath test results, attempts to start the vehicle, and any violations. This data is securely stored within the device and is used to monitor compliance.

Throughout your time in the program, the device will need to be serviced regularly. During these appointments, the recorded data is downloaded and reviewed by the relevant authorities. This ensures you are meeting the requirements needed to progress through and complete the program.

Alcohol interlock devices play an important role in improving road safety by preventing drink driving. They help drivers develop safer habits, reduce repeat offences, and provide a structured pathway to regaining full driving privileges. Ultimately, they protect not only the driver but everyone on the road.