top of page

DUI Metrology Dictionary

duidictionary.com

Ambient Fail

See the CFS Intoxilyzer 8000C Training Aid 2013 p. 136 of 238. "The instrument has detected an unacceptably high alcohol concentration in the ambient air drawn in during the air blank. The ambient fail message is communicated when the difference between the vapours in the sample chamber at cessation of the air blank (i.e. when the pump stops) is more than 10 mg/100 mL higher than the baseline measurement obtained before the pump was activated." With respect, I suggest ambient fail can occur as a result of radio frequency interference AND as a result of the difference between the vapours in the sample chamber being LESS than the baseline floating zero measurement.

Ambient fail exception on an Intoxilyzer 8000
Blog articles on ambient fail and ambient fail threshold

If you are a member of the public, please don't attempt to use what you see or read at this site in Court. It is not evidence. The author is not a scientist. The author has a great deal of experience in cross-examining scientists about these issues, but the author is not a scientist. Hire a criminal lawyer in private practice in Ontario. Your lawyer can retain an expert. The author is a retired lawyer, not a lawyer in private practice. Read the statement of the purpose of this web site below.

© 2025 Allbiss Lawdata Ltd.

This site has been built by Allbiss Lawdata Ltd. All rights reserved. This is not a government web site.

For more information respecting this database or to report misuse contact: Allbiss Lawdata Ltd., Mississauga, Ontario, Canada, 905-273-3322. The author and the participants make no representation or warranty  whatsoever as to the authenticity and reliability of the information contained herein.  WARNING: All information contained herein is provided  for the purpose of discussion and peer review only and should not be construed as formal legal advice. The authors disclaim any and all liability resulting from reliance upon such information. You are strongly encouraged to seek professional legal advice before relying upon any of the information contained herein. Legal advice should be sought directly from a properly retained lawyer or attorney. 

WARNING: Please do not attempt to use any text, image, or video that you see on this site in Court. These comments, images, and videos are NOT EVIDENCE. The Courts will need to hear evidence from a properly qualified expert. The author is not a scientist. The author is not an expert. These pages exist to promote discussion among defence lawyers.

Intoxilyzer®  is a registered trademark of CMI, Inc. The Intoxilyzer® 5000C is an "approved instrument" in Canada.

Breathalyzer® is a registered trademark of Draeger Safety, Inc., Breathalyzer Division. The owner of the trademark is Robert F. Borkenstein and Draeger Safety, Inc. has leased the exclusive rights of use from him. The Breathalyzer® 900 and Breathalyzer® 900A were "approved instruments" in Canada.

Alcotest® is a registered trademark of Draeger Safety, Inc. The Alcotest® 7410 GLC and 6810 are each an "approved screening device" in Canada.

Datamaster®  is a registered trademark of National Patent Analytical Systems, Inc.  The BAC Datamaster® C  is an "approved instrument" in Canada.

bottom of page