Troubleshooting

IID False Positives: What to Do

False positives happen. Here's what causes them, how to prevent them, and what to do if you get one.

Don't panic if you get a false positive

Wait 15 minutes and retest. The second (clean) test is also logged and can demonstrate it wasn't actual alcohol.

If You Get a False Positive

1

Stay calm

A single failed test doesn't mean automatic consequences. The data is reviewed in context.

2

Wait 15 minutes

Any substance causing a false positive should clear quickly. Don't retest immediately—wait the full time.

3

Rinse your mouth with water

Just water—no mouthwash. This helps clear any residue that might have caused the reading.

4

Retest

After waiting, provide another sample. A clean second test strongly suggests false positive.

5

Document what happened

Write down the time, what you ate/drank/used, and circumstances. This helps if you need to explain later.

Common Causes of False Positives

Mouthwash

Very High risk

Most mouthwashes contain alcohol. Residue in mouth can trigger false positive.

Prevention:

Use alcohol-free mouthwash only

Breath spray/mints

High risk

Many contain alcohol or sugar alcohols that can trigger readings.

Prevention:

Avoid spray; use unflavored mints

Hand sanitizer

Medium risk

Alcohol vapors from hands near face during test.

Prevention:

Wash hands before testing; let sanitizer dry completely

Certain foods

Medium risk

Bread, ripe fruit, energy drinks, some sauces.

Prevention:

Wait 15-20 minutes after eating before testing

Medications

Medium risk

Some liquid medicines, cough syrups, cold medications.

Prevention:

Check ingredients; wait after taking

Medical conditions

Low-Medium risk

Diabetes (ketones), GERD, acid reflux can affect readings.

Prevention:

Document condition; retest if failed

Cigarette smoke

Low risk

Can occasionally interfere with some sensors.

Prevention:

Wait a few minutes after smoking

Windshield washer fluid

Low risk

Strong methanol fumes in enclosed car.

Prevention:

Ventilate car before testing

How to Prevent False Positives

Do

  • • Use alcohol-free mouthwash only
  • • Wait 15-20 minutes after eating
  • • Wash hands before testing
  • • Ventilate your car in cold weather
  • • Keep the device clean
  • • Check medication ingredients

Don't

  • • Use regular mouthwash
  • • Test right after eating
  • • Use hand sanitizer near your face
  • • Smoke right before testing
  • • Use breath spray
  • • Panic if you fail once

How to Dispute a False Positive

If you believe a recorded violation was a false positive and it's causing problems, here's how to address it:

1. Gather your evidence

  • • Notes about what you ate/drank/used before the test
  • • Time between initial fail and clean retest
  • • Pattern of clean tests before and after
  • • Documentation of medical conditions if relevant

2. Contact your attorney

A DUI attorney can help present your case to the court or DMV. They know what evidence is most convincing.

3. Request a hearing

If you receive notice of a violation, you typically have the right to a hearing to present your explanation.

4. Show the pattern

A single failed test followed by immediate clean retests, in a pattern of otherwise clean tests, strongly suggests false positive.

Be Honest with Yourself

If you've been drinking, the IID is doing its job. A few things to keep in mind:

  • Alcohol can remain in your system longer than you think—even "sleeping it off" doesn't always clear it
  • The device threshold (0.02-0.025%) is much lower than the legal driving limit
  • Claiming false positive when you've been drinking makes things worse if discovered
  • Camera-equipped devices show your face—they can prove or disprove false positive claims

IID Violations Guide

All types of violations and consequences

Tips & Best Practices

Avoid common IID problems

Sources

Information based on IID provider documentation and scientific literature on breath alcohol testing as of January 8, 2026.