AlcoSense Zero Support

This page contains basic support information and FAQ’s for the AlcoSense Zero. If for any reason your query is not answered below please do not hesitate to contact us


Trouble Shooting & Frequently Asked Questions

The Test Counter Was Not Showing Zero (0) When I Got It. 

This is normal. Every breathalyser we make is tested for accuracy after calibration and before it leaves the factory. The number you see here shows the tests we perform to ensure the highest quality for you.  

I've Got a Positive Reading But I Haven't Drunk Any Alcohol

This can be caused by several reasons:
  • The first test after the unit has cleaned itself (when you insert new batteries or after every 30 tests) can sometimes show a small reading when you have had no alcohol. This is because the sensor burns off contaminents when it cleans itself, sometimes the vapour from this process can still be in the unit and it is picked up. After 10 minutes this clears, or you can blow though the unit to clear this.
  • Testing within 10 minutes of eating some strong foods, using dental products, chewing gum or smoking.
  • On some occasions it can also be caused by the body releasing acetone/ketones during the metabolism of acetoacetic acid. This can be increased with the use of some prescribed medications or certain medical conditions, most commonly diabetes. A healthy body can also create these substances occasionally, it is more likely if you are on a low carbohydrate diet such as the Atkins diet or similar.
If you experience this issue and it is not caused by any of the above, please call us. 

I'm doing a breath test and it says FLO or ERR

Either the pressure you blew at was too variable or you did not blow for long enough. Take a deep breath before blowing and blow out at a consistent pressure like you’re taking a sigh until you hear the double beep. If you have any problems please call us.

Either the breathalyser did not detect your breath as the pressure was too low, or you did not blow into the breathalyser within 10 seconds of it starting to say blow on the screen. If you still experience problems after several attempts please contact us.

"Calibrate Now" is shown on the screen

Like any breathalyser, whether for Police use of otherwise, your AlcoSense will require re-calibration after a period of use. We recommend your AlcoSense breathalyser should be re-calibrated once a year or every 300 tests, whichever comes first. If you do not have your breathalyser calibrated within these schedules it may read inaccurately. When you turn your breathalyser on it will display how many tests it has done during the first 3 seconds. After 300 tests you breathalyser will display
“Recalibrate Now” on the screen. Recalibration is a chargeable service, but necessary to maintain the accuracy of your breathalyser. When this appears, go to the calibration section of our website by clicking here to arrange your calibration.

I've done two breath tests and got different results

This is expected. The first test is the most accurate, if you perform a second test within a few minutes of the first test the breath alcohol levels in your lungs may not have stabilised after the first test, causing the second test to give you a different reading. If you have recently drunk alcohol, your blood alcohol level can also change quickly over the course of a few minutes. This is why you should only use the breathalyser 90 minutes after drinking or ideally, the morning after. If you test two different breathalysers back to back you will also expect slightly different readings for the same reason. This is why you cannot use one breathalyser to test the accuracy of another, it can only be done using Breath Alcohol Simulators. This is why UK law allows for up to 15% difference on sequential test results taken by the Police.

How Do Breathalysers Work?

The AlcoSense™ Zero breathalyser measures the concentration of alcohol vapour in a person's breath. Contrary to popular belief the alcohol is not coming from residue in the person's mouth but is actually evaporating from the blood that passed through the lungs when breathing. The amount of alcohol evaporating from the lungs is directly proportional to the amount of alcohol in the person's blood stream making it possible to accurately judge the persons level of intoxication.

How Alcohol Is Processed by the Body

When you drink, alcohol is absorbed into the blood stream through the stomach and small intestine. The more you drink the more is absorbed. After approximately one hour the alcohol is distributed equally around the blood stream.

As blood flows round the body around 90% of the alcohol it contains is broken down in to water and carbon dioxide by the liver in a process called oxidation. The remaining 10% of the alcohol is passed through the lungs and kidneys. A healthy liver typically breaks down alcohol at a rate of one hour per unit of alcohol but the more alcohol that is consumed the longer it can take for the liver to process each unit.

When you stop drinking your level of intoxication may stay constant or if you have been drinking heavily it could even increase for around 2 hours afterwards. This is because of the time it takes for alcohol to reach the bloodstream from the time you actually had the drink. If you have eaten food this can also increase this time as the release of alcohol into the bloodstream can be slowed by being absorbed by the food in the stomach. This is the reason why we do not recommend the use of this breathalyser just after finishing drinking because there are so many factors that influence the reading. The ideal time is the morning after.

I had a drink then did a breath test and the reading was high, why is this?

If you perform a breath test less than 10 minutes after drinking the reading will be falsely high. This is because the AlcoSense™ will be taking a reading of the residual alcohol in your mouth, not the alcohol which is being expelled from your lungs which is needed for an accurate reading. After 10 minutes all of the alcohol residue has normally left your mouth and an accurate reading can be made. Please be aware that performing a breath test straight after drinking some alcohol can damage the sensor causing it to read inaccurately in the future. Please also see How Breathalysers Work, above.

How long do I need to wait after consuming alcohol, eating or smoking to perform a breath test?

You should wait at least 30 minutes after eating, drinking or smoking before performing a breath test. On some occasions, if you have drunk heavily, very quickly, it is advisable to wait up to 90 minutes before performing a breath test to allow the alcohol you have drunk to get from the stomach and into your blood stream. For more information please see above section explaining 'how alcohol is processed by the body'.

What factors can affect the reading of my AlcoSense™?

There are some factors that that can affect the reading of breathalysers whether it be a police system or your AlcoSense™. As long as you are aware of these factors you will be able to use your AlcoSense™ Zero accuratley and safely. To help you here is a list of do's and don'ts.


  • Use the breathalyser the morning after a big night.
  • Read the instructions carefully
  • Perform a Clean Program regularly
  • Phone us if you have any difficulties


  • Use the breathalyser for at least 30 minutes after drinking alcohol (we recommend using it the morning after, please see section “How Alcohol is Processed by the Body” in the manual)
  • Use the breathalyser for at least 30 minutes after using mouthwash, breath spray, cough medicine or anything else that may contain alcohol. This may give you a false positive reading (i.e. showing alcohol when you haven't drunk any).
  • Use the breathalyser for at least 30 minutes after having a cigarette or eating certain over-ripe fruit. This may give you a false positive reading (i.e. showing alcohol when you haven't drunk any).
  • Perform a test in dirty air, i.e. a smokey room.
  • Use the breathalyser if you are breathing quickly (for example, after running up the stairs) or have been holding your breath. This can falsely lower or raise the reading respectively. Wait until you are breathing at your normal pace again.

How do I perform a breath test?

Please refer to Section 8 of your operating manual. If you do not have your copy of the operating manual to hand you can download it by clicking the link at the top of this page, under "Downloads".

How long should I blow for?

When the AlcoSense™ unit has finished it's countdown and displays "Blow" on the screen you should start to blow through the tube. You will need to blow for around 5-7 seconds. When blowing at the right pressure the AlcoSense™ Zero will make a constant beep. When it has had enough breath pass through it, it will beep twice. Try blowing like you're taking a sigh (not strongly) and you should be able to blow until the beep. If you stop blowing too soon the unit will display an error.  

How accurate is AlcoSense™?

It is accurate to +/- 0.2‰BAC (Blood Alcohol Content). This means that if you see a reading 0.2‰BAC lower than the legal limit, you could be over the limit. For example, if you are using the unit in England the legal limit is 0.8‰BAC, if you see a reading of 0.6‰BAC do NOT drive. Taking into account all variables, you could be at the legal limit. Any amount of alcohol affects your ability to drive - we only recommend driving when you feel 100% and are completely clear of alcohol. 

My AlcoSense™ won't turn on

Please press and hold the power button for 2 seconds. If it does not start at this point please check that the batteries are inserted in the correct direction and that they have charge. Only use 3 good quality batteries in the device that are all new. Do not insert a mixture of batteries with unknown charge levels as this can affect the accuracy of the device. If this does not solve the issue please call us on 0800 195 0088.

I've run out of blow tubes, how do I get more?

You can purchase them from our on-line store or from your local dealer.

None of the above assist me with my problem

Please call technical support on 0800 195 0088, Mon to Fri 9am to 5.30 pm.