An ignition interlock violation in North Carolina is not one thing. The statute treats a failed start attempt, a removed device, and a tampered device as three different problems with three different consequences, and only one of them is a new crime on its own. Getting that distinction right is usually the difference between a letter from the Division and a Class 1 misdemeanor.
The requirement itself comes from NCGS 20-17.8. If you are still working out whether the interlock applies to you at all, how long it runs, or what it costs, start with our guide to North Carolina ignition interlock requirements under NCGS 20-17.8. This page is about what happens after something goes wrong.
The five ways to violate, and what each one actually costs
Every row below is drawn from the statute rather than from vendor literature. The consequences are not interchangeable.
| What happened | Authority | Consequence |
|---|---|---|
| You drove a vehicle without a functioning approved interlock, did not personally activate it, drove with an alcohol concentration of 0.02 or more, or drove a vehicle you never designated, and you are charged | NCGS 20-17.8(f), NCGS 20-28(a1) | Class 1 misdemeanor for driving while license revoked for impaired driving. On conviction the license is revoked for an additional year for a first offense, two years for a second, and permanently for a third or later. Once a judicial official finds probable cause, the license is suspended while the case is pending and must be surrendered. |
| The same conduct, but you are not charged or convicted of driving while license revoked | NCGS 20-17.8(g) | The Division revokes the license for one year. This is administrative, not criminal. |
| You tampered with, circumvented, or attempted to circumvent the device | NCGS 20-17.8A | Class 1 misdemeanor. The statute states that each act of tampering, circumvention, or attempted circumvention is a separate violation, so repeated attempts stack as separate counts. |
| You removed the device from a designated vehicle, other than when changing providers or on sale of that vehicle | NCGS 20-17.8(c1) | The Commissioner shall cancel the drivers license. The same subsection allows cancellation for operating any vehicle that was not designated and equipped. |
| Any interlock violation during the final 90 days of your term | NCGS 20-17.8(g1) | The requirement is extended by a further 90 days, or until you have been violation free for that extended period. |
Removing the device early cancels your license
NCGS 20-17.8(c1) requires you to designate the registered vehicles you own and operate or intend to operate, and to equip them. The Commissioner will not issue the license at all until shown proof of installation in at least one designated vehicle. After that, the subsection gives the Commissioner authority to cancel the license for removing the device from any designated vehicle.
There are exactly two carve outs written into the statute: changing interlock providers, and sale of the designated vehicle. Nothing else in the subsection excuses removal, including a vehicle that stops running or is off the road.
Tampering is its own crime, under its own statute
Tampering is frequently mis-cited to NCGS 20-17.8. It has its own section. NCGS 20-17.8A makes it a Class 1 misdemeanor to tamper with, circumvent, or attempt to circumvent an interlock device required by judicial order, statute, or as a condition of driving, where the purpose is to avoid or alter testing, or to alter results that were received or are in the process of being received.
Two features of that section matter in practice. It reaches an attempt, so an unsuccessful workaround is still chargeable. And each act is a separate violation, so a pattern in the data log can support more than one count.
A violation does not restart your interlock period
This is the single most common piece of misinformation about the North Carolina program, and it appears on a great many websites. The statute says the opposite.
NCGS 20-17.8(k) provides that when the Division restores a license after a revocation under subsection (f) or (g), the time you already spent complying with subsection (b) before that revocation is applied toward the period required by subsection (c). Time served counts. Separately, NCGS 20-17.8(d) provides that if you held a limited driving privilege carrying the interlock condition in NCGS 20-179.3(g5), that period also counts toward the requirement.
The only extension the statute actually authorises is the 90 day extension in subsection (g1), and it applies only to a violation in the final 90 day window. There is no provision anywhere in NCGS 20-17.8 that resets the clock to zero.
The 90 day trap at the end of your term
NCGS 20-17.8(g1) is the provision people are caught by, because it applies precisely when they have relaxed. A violation during the 90 days immediately preceding the scheduled end of your interlock term extends the requirement another 90 days, or until you have gone violation free for that extended period.
For that subsection, an interlock system violation means any of three things: an attempt to start the vehicle with an alcohol concentration greater than 0.02 or a breach of the other subsection (b) restrictions, a violation of NCGS 20-17.8A, or a violation of any Division policy governing use of the device on a designated vehicle. The Division must notify you of the violation and of your right to appeal, and it must provide a telephonic hearing if you appeal. Note that the extension continues while the appeal is pending.
What an interlock report can and cannot prove
This is the part of the statute that most competitor pages omit, and it is the one worth knowing before you concede anything to the Division.
NCGS 20-17.8(f) states that an alcohol concentration report from the ignition interlock system is not admissible as evidence of driving while license revoked, and is not admissible in the administrative revocation proceeding under subsection (g), unless the person operated a vehicle when the device indicated an alcohol concentration in violation of the restriction in subsection (b)(3).
The practical consequence is direct. A failed start attempt, standing alone, is a reading with no accompanying operation of the vehicle. Someone who blows, gets a lockout, and never moves the car has generated a data point that the statute makes inadmissible for these purposes. To use the report, the State or the Division has to connect the violating reading to actual operation of a vehicle. That is an evidentiary question, and it is often the whole case.
It is also why the vendor data log matters so much. NCGS 20-17.8(b)(1) requires approved vendors to report every attempt to start the vehicle with an alcohol concentration greater than 0.02, along with other policy violations, to the Commissioner. The log is generated whether or not anyone drove.
Your hearing rights, and where the hearing is held
If the Division revokes under subsection (g), NCGS 20-17.8(i) makes the revocation effective on the thirtieth calendar day after the revocation order is mailed. Before that effective date you may request a hearing in writing. If you request it properly, you keep your license until the hearing is held, unless it is revoked under some other provision.
The hearing is narrow by statute. Under NCGS 20-17.8(j) it is limited to whether your license carried an interlock requirement, and whether any of four things occurred: you drove a vehicle without a functioning device, you did not personally activate it, you drove in violation of the 0.02 restriction, or you drove a vehicle that was not designated. If the Division finds the first condition unmet, or none of the four, it must rescind the revocation.
One detail is worth planning around. The hearing is normally held in the county where the charge was brought, but NCGS 20-17.8(j) provides that where the evidence of the violation is an alcohol concentration report from the interlock system, the hearing may be held in the county where the person resides. You may also request that the hearing officer subpoena the charging officer, the chemical analyst, or both, if you ask in writing at least three days before the hearing.
Frequently asked questions about ignition interlock violations in North Carolina
How many interlock violations can you have in North Carolina? The statute does not set a numeric allowance. NCGS 20-17.8 works by consequence rather than by count. A single violation can support a Class 1 misdemeanor under subsection (f) if you are charged, or a one year administrative revocation under subsection (g) if you are not. A single violation in the final 90 days triggers the 90 day extension in subsection (g1). There is no free allotment before consequences attach.
What happens if I remove my interlock device? NCGS 20-17.8(c1) authorises the Commissioner to cancel your drivers license for removing the device from a designated vehicle. The only two exceptions written into the subsection are changing interlock providers and sale of the designated vehicle. A vehicle that is broken down or off the road is not an exception in the statute.
Does an interlock violation restart my interlock period in North Carolina? No. NCGS 20-17.8(k) provides that time you already spent in compliance is applied toward the period required by subsection (c), and NCGS 20-17.8(d) credits time spent on a limited driving privilege that carried the interlock condition. The only extension the statute authorises is the additional 90 days under subsection (g1) for a violation in the final 90 day window.
Can the DMV use my interlock report against me? Only in limited circumstances. NCGS 20-17.8(f) makes an alcohol concentration report from the device inadmissible as evidence of driving while license revoked, and inadmissible in the subsection (g) administrative proceeding, unless the person actually operated a vehicle when the device registered a reading violating the 0.02 restriction. A failed start with no operation of the vehicle does not meet that condition.
What is a Monitech or Smart Start violation in North Carolina? Those are vendor names, not legal categories. What the vendor logs as a violation, warning, or lockout is a business record generated under the vendor’s own policies. The legal consequence depends on which statutory provision the conduct falls under, whether the Division proceeds under subsection (f) or subsection (g), and whether the report is admissible at all under the evidentiary limit in subsection (f).
How do I get the interlock removed by NC DMV? The requirement ends when you have completed the period set by NCGS 20-17.8(c), which is one year from restoration if the original revocation was one year, three years if it was four years, and seven years if the revocation was permanent. Time already served in compliance counts under subsection (k), and time on a qualifying limited driving privilege counts under subsection (d). If you committed a violation in the final 90 days, subsection (g1) extends the period until you have been violation free for the extended term.
Talk to a North Carolina DWI lawyer before you respond to the Division
An interlock notice has a deadline attached to it. The revocation takes effect on the thirtieth calendar day after the order is mailed, and the written hearing request has to be in before that date. If you have received a violation notice, or you are facing a charge under NCGS 20-28(a1) or NCGS 20-17.8A, call Martine Law at (704) 461-9488. Free consultation, available 24/7.
