Alcohol immobilizer

DonĀ“t drink and drive

Alcohol immobilizer

AlcoWarn’s alcohol immobilizer or “breath alcohol ignition interlock device” (BAIID) prevents the vehicle from starting under the influence of alcohol.

PreLock 90, the alcohol immobilizer from AlcoWarn

The alcohol immobilizer consists of two parts: a hand-held device with a measuring indicator and a control unit, which is installed under the dashboard cover and within reach of the driver’s seat.

Alcohol immobilizer from AlcoWarn
Alcohol immobilizer from AlcoWarn

PreLock 90 from AlcoWarn

The driver first operates the ignition.

Then, for example, a signal tone or an LED light on the hand-held device prompts the user to provide a breath sample.

The handheld device measures the alcohol concentration in the breath and after about five seconds the result is shown on the display.

AlcoWarn’s alcohol immobilizer has several impressive features.

First, it is based on reliable and accurate technology that can precisely measure alcohol content in the breath. This ensures that drivers cannot drive under the influence of alcohol.

Secondly, the alcohol immobilizer is user-friendly. It is easy to operate and has a clearly visible display that gives clear instructions. This allows drivers to quickly see whether they are fit to drive or not.

In addition, AlcoWarn offers excellent customer service and support. In case of any questions or problems, the team is always available to provide support.

In conclusion, AlcoWarn’s immobilizer stands out for its precision, ease of use and excellent customer service. It is a reliable solution to prevent drunk driving, making the roads safer. Moreover, the immobilizer is very sturdy and durable. It has been made from high-quality materials to withstand the rigors of daily use. This ensures that it will work reliably even in adverse weather conditions or other challenges.

Another advantage of the AlcoWarn breath alcohol immobilizer is its flexibility. It can be installed in different types of vehicles and is suitable for both private and commercial use. It also offers various options for personalization, such as individual settings for breath alcohol content or special warnings.

Last but not least, the use of such an immobilizer helps to raise awareness of the issue of “drinking and driving” and thus reduce road traffic accident figures in the long term.

Overall, the AlcoWarn alcohol immobilizer convinces with its high quality as well as its usefulness in improving road safety on our roads. Its reliable function and flexibility make it a sensible investment for every vehicle owner who wants to take responsibility in road traffic.

Installing such an immobilizer can help prevent serious accidents caused by drunk driving and thus save lives.

With this innovative technology, AlcoWarn sets an example against drunk driving and makes an important contribution to improving traffic safety on our roads.

How an alcohol immobilizer works

The process of using it is quite simple:

  • The driver turns the ignition key to start.
  • Mandatory administration of a breathalyzer test is indicated.
  • Through a mouthpiece (replaceable for hygienic reasons) on the hand-held device, the driver gives a breath sample.
  • After approx. 5 seconds, the result of the breath alcohol content is shown on the display of the hand-held device.
  • Only if the previously entered limit values are not exceeded, the ignition is enabled.
  • Nothing stands in the way of an alcohol-free and therefore safe journey in road traffic.


An alcohol immobilizer, also called an Ignition Interlock Device, Alkolock or Alcohol Interlock, combines a breathalyzer with an immobilizer. By performing a breath alcohol test before starting the engine, the driver who is under the influence of alcohol is prevented from starting the vehicle engine.

An alcohol immobilizer thus protects other road users from a possible drunk driving accident. Alcohol interlock devices can be used to prevent this.

Alcolock’s alcohol immobilizer is a combination of a handheld meter, which is placed within reach of the driver, and a control unit, which is usually installed underneath the dashboard cover.

The driver gives his breath sample to the hand-held device via a mouthpiece. The integrated breath alcohol measuring device measures the alcohol content of the breath sample. Each breath sample given or also aborted are stored. If a test of the breath alcohol content reveals that a stored limit value has been exceeded, the ignition of the motor vehicle is blocked.

Only a positive breath test can enable the ignition of the vehicle. Both components form a reliable unit designed to prevent drunk driving.

Alcohol interlocks and alcohol immobilizers are the same systems. Only the terminology for an alcohol meter combined with an immobilizer was presented differently.

In accident research and thus also in legal texts, the English term “Alcohol Interlock” has become established, which has been translated into German as “Alkohol Interlock”.

However, the factually correct German term is “Alkoholwegfahrsperre”.

An alcohol ignition interlock consists of two important components:

A handheld device as a breath alcohol measuring device with the integrated alcohol measuring technology, a control device with an additional data memory and the interlocking technology to prevent the engine start.

Some immobilizers have an additional external relay that is triggered and prevents the engine from starting.

For hygienic reasons, a mouthpiece is inserted into the handheld unit through which the breath sample is delivered. Depending on the type of unit, each procedure is recorded in the data memory of the handheld unit or in the memory of the main unit so that they can be evaluated later.

First, the driver turns the ignition key so that the ignition is activated by the vehicle. The hand-held device indicates that it is ready for operation and the mandatory administration of a breath alcohol test is displayed.

The driver now gives a breath sample via a mouthpiece on the handheld device, just as it works with the police rapid test devices.

After about 5 seconds, any breath alcohol content is displayed. If this exceeds the legal maximum (preset in the system), the ignition is blocked. This is to prevent driving a motor vehicle under the influence of alcohol.

An alcohol immobilizer serves as an immobilizer in general and improvement of road safety in particular. Thus, such an alcohol immobilizer can be applied for funding via de minimis. A subsidy of up to 80% of the total acquisition costs (immobilizer + installation of the immobilizer in the vehicle) is possible.

Eligible super-mandatory measures include: “Breathalyzers with automatic immobilizer.”

Drivers’ mistakes are still the most common cause of accidents on the road. In addition to inappropriate speed, risky overtaking maneuvers and disregard for the right of way, many accidents are also due to driving under the influence of alcohol. The use of so-called alcohol interlocks can help here.

Accident research figures show that alcohol in road traffic is still a major source of danger.

One way of counteracting this risk of accidents, among many other measures, is media campaigns against drinking and driving and a zero alcohol limit regulation. In particular, this includes the use of alcohol interlocks.

The calibration intervals for alcohol immobilizers are specified by the legal framework. Currently, calibration must be performed every 12 months.

The alcohol measuring units in the handheld units of alcohol immobilizers are highly sophisticated and very accurate measuring instruments.

In order for these to be able to determine reliable measured values for each breath sample, the units must be regularly cleaned and checked for their measuring accuracy. Since the measurement results must also comply with legal framework conditions and may also be used in part due to court orders, regular inspection and maintenance of the measurement units is indispensable.

Before the breath sample, make sure that you have not eaten or drunk anything for at least 10 minutes beforehand. Optimally, rinse the mouth and throat with water so that the breath is free of other particles from the mouth and throat.

Do not eat any spicy or mentholated sweets for at least 30 minutes before the breath test, nor any food containing alcohol, such as chocolates filled with alcohol.

Do not use disinfectants, windshield washer fluid or de-icer spray directly before the breath test, as these can release alcohol particles into the ambient air and thus into the breath.

Breathe evenly and calmly into the mouthpiece as soon as the hand unit prompts you to take a breath sample.

The measurement of alcohol on breath involves very small and very small particles of alcohol in the breath.

An alcohol content as low as 0.01 per mille can be measured, which corresponds to only a few particles in the breath.
Thus, substances similar to alcohol or substances in the air that behave similarly can also have a negative effect on the test result, such as windshield cleaner containing alcohol, which can enter the vehicle through the ventilation.

Scent fresheners in the vehicle, disinfectant on the hands or used for surface disinfection in the vehicle, as well as freshly applied perfume, are also part of this. Spicy lozenges such as Fischerman’s Friend or menthol candies, as well as mouthwash, can also negatively affect the breath test.

Negatively affect breath sample. These include:

  • Disinfectant on hands, clothing or vehicle surfaces
  • Window cleaner with alcohol, which after spraying penetrates through the ventilation into the vehicle interior
  • Fragrance fresheners which were sprayed in the vehicle
  • Fresh or extensively applied perfume
  • A heavily intoxicated passenger

Ventilate the vehicle interior extensively for several minutes and perform the next breath test with the windows or doors open.

Spicy lozenges, such as menthol candies or Fischerman’s Friend or even a chocolate with alcohol content can also lead to an adulterated breath sample. Rinse the mouth several times and extensively with water until the breath is again free of any substances mentioned.

Breath alcohol immobilizers approved in Europe detect whether a human breath sample is involved or whether the air stream is delivered by other mechanical air streams.

Human breath samples have well measurable breathing patterns and are thus also clearly identifiable as human breath samples. Other airflows, which are delivered to the measuring device as a fictitious breath sample, can very easily be identified as manipulation.

A detected manipulation is documented by the main unit and can later be identified as a manipulation attempt when evaluating the device data.

Especially in the case of legally ordered alcohol immobilizers, several recorded tampering attempts can lead to an extension of the order.

Thus, it is strongly discouraged to try this even just for fun!

Alcohol immobilizers are hygienically unproblematic because each driver uses his own interchangeable mouthpiece.

The mouthpieces can be repurchased inexpensively; they are also designated as disposable mouthpieces. For sustainability reasons, however, it is advisable to use a used mouthpiece several times and to rinse it regularly with hot water.

As soon as a mouthpiece shows signs of contamination, it should be replaced immediately with a new mouthpiece.

The brand Prelock is composed of “Pre” of the English term “preventive” and the English word “lock”.

Thus, the sensible translation for PreLock = Preventive locking – by a breath alcohol test.

Our competent service staff is here for you and happy to answer your questions:

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