What an ignition interlock device is
An ignition interlock device — a car breathalyzer, an IID, a BAIID in Illinois, a CIID in Arizona, a «blow and go» anywhere people are talking rather than filing — is a breath alcohol tester wired between your ignition and your engine. Blow clean and the car starts. Blow over your state’s threshold and it will not. Everything else on this page is the part nobody explains: how much air it wants, what the camera is looking at, and how long you have before it stops the car for a reason that has nothing to do with drinking.
The handset
A mouthpiece and sensor unit that sits in the cabin, usually clipped near the wheel.
The relay
Wiring in the engine bay that holds the starter circuit open until a clean sample is given.
The log
Memory that records every test, lockout and start, downloaded at each service visit.
The sensor, and a claim worth correcting
Commenters asked NHTSA to require fuel cell technology and ban semiconductors. The agency declined: requiring one technology or prohibiting another would set a design standard rather than a performance one. What the specifications do demand is the result — under tests 12 and 13 a device has to tell alcohol apart from substances commonly found on breath, naming acetone and cigarette smoke, and one that cannot is out of conformance.
The first interlock was built in 1969 and the early sensors were inconsistent at reading alcohol correctly. Manufacturers moved to fuel cell sensors in the early 1990s, and that is the technology in use today. So the honest version of the familiar claim is this: your device very probably uses a fuel cell because the industry settled there, not because a regulation says it must.
Rolling retests
After you set off, the device prompts you again at random. For safety reasons the device cannot turn off the ignition once the vehicle has started — the fear of being stranded mid-junction is unfounded. What a failed or missed retest does instead is warn you and set off an alert: the horn, the lights, or both, continuing until the ignition is switched off or an acceptable sample is given. The event is logged either way.
NHTSA had proposed language saying retests were not intended to be taken while the vehicle is moving, but with the engine running and the car stopped safely at the roadside. After comments it removed that wording from both the preamble and the specifications, and no longer says how a retest should be conducted. So the rule that binds you is your state’s and your monitor’s, not a federal one.
What gets reported, and to whom
Your logs go to whoever is monitoring your case: the court, the DMV or the state agency that issued the restricted license. What counts as a violation, and what a violation costs you, is set by that state — see the rules where you live. What the agency counts as a violation, and what it adds to your term, is a separate question with its own arithmetic — what a violation actually costs.
Coming off is its own procedure, and it is not the one most people assume: the state releases you first and the workshop unbolts the device last — how removal and waivers work.
One device is regularly confused with this one. A transdermal ankle bracelet also measures alcohol, but it watches the person rather than the car and says nothing about driving at all — how continuous monitoring differs.
What your state calls it, and why the letters matter
People search for the abbreviation on their own paperwork, and the abbreviations do not mean quite the same thing. One of them is not even a device.
| Term | Stands for | Where, and what it changes |
|---|---|---|
| IID | Ignition interlock device | Most states, and the usual name in court paperwork. The default term, and the one to search with if you do not know what your own state calls it. NHTSA, Model Specifications for BAIIDs · checked 2026-09-04 |
| BAIID | Breath alcohol ignition interlock device | Illinois, New Jersey, and the federal specifications. Illinois defines it as an alcohol monitoring device installed in the ignition that will not let the vehicle start at a BAC of 0.025 or more, and the state additionally requires a camera unit to photograph the driver giving the sample. If your letter says BAIID, the camera is not optional equipment. Illinois Secretary of State, about BAIID · checked 2026-09-04 |
| CIID | Certified ignition interlock device | Arizona. Arizona certifies devices and installers, and the word “certified” carries weight: the order you receive lists the approved manufacturers, and an installation by anyone else does not count as compliance. Arizona MVD, certified ignition interlock device pamphlet · checked 2026-09-04 |
| IIL | Ignition interlock driver license | Washington. The trap in this one is that it names a license type rather than a piece of hardware. An IIL is the restricted license that lets you drive at all during the restriction; the device is a condition of holding it. Washington DOL, ignition interlock driver license · checked 2026-09-04 |
| MDDP | Monitoring device driving permit | Illinois. A first-time offender in Illinois is enrolled automatically, and the permit allows driving around the clock during the statutory summary suspension — but only in a vehicle fitted with a BAIID, and only if the device goes in within 14 days of the permit being issued. Illinois Secretary of State, MDDP · checked 2026-09-04 |
«Blow and go» belongs in a different column again: it is what people call the thing in conversation, and also a trading name in the industry — see the provider of that name if that is what you were looking for.
How much air the device actually wants
Most people who think their device is broken are giving it a sharp puff from the mouth. The federal conformance tests measure two separate things, volume and flow, and a short breath fails both by design.
A short puff is designed to fail
This is the mechanical answer to trouble blowing into the device. The conformance tests measure both how much air you give and how hard: a device is checked against sample volumes of 1.0 and 1.5 liters and flow rates of 0.1 and 0.7 liters per second, and it is expected not to start the car on the smaller volume. A short, weak breath is not a malfunction when it is refused — it is the specification working. Give a long, steady breath from the chest rather than a sharp blow from the mouth.
NHTSA, Model Specifications for BAIIDs · 78 FR 26849, tests 2a–2d
Three minutes, and it is ready again
The 2013 revision replaced a confusing set of different waiting times with one: a device must be ready for every test and retest within three minutes. If yours is still refusing to accept a sample well beyond that, the problem is the device or the service interval, not your technique.
The workarounds are on the federal test sheet
Test 9 exists precisely because people try. Among the conformance checks are a warmed, humidified air sample and a sample passed through an absorbent filter — and in both the vehicle must not start. We do not publish the methods; the point is the opposite one. Anything you have read about is old enough that the federal test procedure already covers it, and the device that fails those tests never reaches a state list.
If you genuinely cannot produce the sample — a lung condition rather than a technique problem — that is not a conversation with the installer. It is a medical exemption, and the states that grant one want a physician, not a receipt: where the medical exemption exists and what it takes. Mouthwash, some medicines and anything else containing alcohol will read as alcohol, because the device is measuring your breath and not your intentions.
How long you have to install it
The deadline is the part that costs money, because in most states the clock on your term does not start until the device is in and the paperwork has landed. Waiting a month does not shorten anything — it delays the end by a month.
| State | Deadline | What it covers, and the source |
|---|---|---|
| New York | 10 days from sentencing | The clock starts at sentencing, or at release if you are sentenced to a prison term, and the sooner the device goes in the sooner your time begins to run. Your monitor — the county STOP DWI program, the district attorney or probation — supplies the list of approved installers. Proof of installation goes to the court within three days. If you do not own the car, bring a notarized statement from the owner allowing the device to be fitted. New York Courts, ignition interlock device · N.Y. Veh. & Traf. Law § 1198 · checked 2026-09-04 |
| Illinois | 14 days from the permit | The permit comes first and the device follows: once the MDDP is issued you have 14 days to fit a BAIID in every vehicle you intend to drive during the suspension, and finding an approved vendor is your job, not the state’s. The permit itself allows the trips to and from the installer. Illinois Secretary of State, MDDP · 92 Ill. Adm. Code 1001.441 · checked 2026-09-04 |
| Arizona | 30 days from conviction | Failing to have the device installed and to give MVD the verification within 30 days of conviction may bring an immediate suspension of your Arizona driving privilege and an extension of the original interlock requirement. Note which two things the deadline covers: fitting the device, and the paperwork reaching the department. Arizona MVD, certified ignition interlock device pamphlet · A.R.S. § 28-1461 · checked 2026-09-04 |
| California | Before the restriction can be cleared | California runs it on documents rather than days: you arrange installation with a certified provider and then file the “Verification of Installation” form with the department. Until that form arrives, the record still shows an unmet requirement no matter what is bolted into the car. California Vehicle Code § 23575.3 · Cal. Veh. Code § 23575.3(d)(1)(B) · checked 2026-09-04 |
Calibration, and the week you get before the car dies
The specifications set a minimum calibration stability period of 37 days — 30 days plus a seven-day lockout countdown — and let manufacturers demonstrate longer stability at 60, 90 or 180 days plus seven. That seven-day tail is the warning period before the car stops starting, which is why a missed service appointment turns into a dead vehicle roughly a week later rather than immediately.
| State | Interval | Detail and source |
|---|---|---|
| Illinois | First report at 30 days, then every 60 | Illinois wants the first monitor report inside 30 days specifically so you learn to use the device correctly, and after that not longer than every 60 days for calibration and reporting. Pick up a violation extension and monitoring moves to every 30 days. There is also a hard backstop: reports must reach the Secretary within 67 days of the previous one, and if they do not, you get a letter giving you 10 days before the permit is canceled. Illinois Administrative Code, section 1001.441 · 92 Ill. Adm. Code 1001.441(h) · checked 2026-09-04 |
| Arizona | Calibration every 90 days | Once installed, the device must be calibrated and inspected by a certified installer every 90 days, and the manufacturer submits the compliance check electronically. You are not the one filing it, but you are the one whose privilege is suspended if it does not arrive. Arizona MVD, certified ignition interlock device pamphlet · A.R.S. § 28-1461; A.A.C. R17-5-610 · checked 2026-09-04 |
A missed appointment is a violation in its own right in most programs, quite separately from the lockout — what that adds to your term.
What the camera on an interlock is looking at
Not your face, exactly. The rules that describe the shot describe a frame wide enough to answer two questions the state cares about, and both are about who is blowing.
The angle is written into the rules
Illinois does not just require a camera, it specifies what the frame has to show: the image must be clear and accurate, and wide enough to establish whether the person blowing is sitting in the driver’s seat and whether anything has been inserted into the mouthpiece. Two consequences follow. If the images at the time of a violation show the camera was blocked, your written explanation is rejected automatically. And if the camera is obstructed or badly aimed after the state has told you to fix it, the permit can be canceled on that alone.
Illinois Administrative Code, section 1001.441 · 92 Ill. Adm. Code 1001.441(h)(6), (i)(7)–(8) · checked 2026-09-04
Whoever drives your car has to blow, and it is on you
The permit terms say it plainly: anyone driving your vehicle must use the device, you are responsible for everything it records, and it is your job to tell them how to use it and where the camera is. A friend borrowing the car and blocking the lens is your violation, not theirs.
Illinois Secretary of State, MDDP terms and conditions · MDDP terms, sections 2 and 3 · checked 2026-09-04
Which models states actually approve
You do not choose a device the way you choose a phone. Your state keeps a list of approved models, and the name on your paperwork has to be on it. Below is what the published lists say — the same brand often appears under a different model number in each state.
| Provider | Model on the list | State and source |
|---|---|---|
| Guardian Interlock | AMS 2000 and AMS 2500 | Texas · checked 2026-08-30 |
| Intoxalock | 1001A | Florida · checked 2026-08-30 |
| Intoxalock | 1001A | Texas · checked 2026-08-30 |
| LifeSafer | L250 | Florida · checked 2026-08-30 |
| LifeSafer | FC100 and L250 | Texas · checked 2026-08-30 |
| Low Cost Interlock | LCI-777 | Arizona · checked 2026-08-30 |
| Low Cost Interlock | LCI 750, TAB 720 and LCI-777 | Texas · checked 2026-08-30 |
| Monitech | QT-1L | Texas · checked 2026-08-30 |
| QuickStart Interlock | QT2 | Arizona · checked 2026-08-30 |
| RoadGuard Interlock | Draeger Interlock 7000 | Florida · checked 2026-08-30 |
| Simple Interlock | Co-Pilot | Georgia · checked 2026-08-30 |
| Simple Interlock | Co-Pilot | Texas · checked 2026-08-30 |
| Smart Start | SSI1000, SSI 20/20, SSI 20/30, SSI-2035 and Flex 3030 | Texas · checked 2026-08-30 |
A model approved in one state is not automatically approved in the next. If your case moves across a state line, the device may have to be swapped even though the brand stays the same — and the clock on your term does not stop while you arrange it.
Common questions about the device
Do police know if you have an interlock device?
Yes. An interlock requirement is normally recorded as a restriction on your driving record and license, so it is visible to an officer who runs your details during a stop.
The device itself also logs every breath sample and reports to the monitoring authority on the schedule your state sets.
Can I drink one beer with an interlock installed?
An interlock will lock you out at a breath alcohol level far below the legal driving limit, and the threshold is set by your state, not by you. One drink shortly before a test is enough to trigger a failed reading on most devices.
A failed test is logged. Depending on your state, a pattern of failed tests can extend your interlock term or trigger a violation review.
What does an ignition interlock device do?
An ignition interlock is a breath-alcohol tester wired into your car ignition. You blow into it before starting the engine; if your breath alcohol is above the state threshold, the engine will not start.
While you are driving, the device asks for rolling retests at random intervals. Every sample, skipped test, and lockout is recorded and sent to the agency monitoring your case.