How Many DUIs Require a Car Breathalyzer in Texas?

In Texas, a single DWI can require an ignition interlock device — the court-ordered breathalyzer wired into your car — when your blood alcohol concentration was 0.15% or higher, when a child was in the vehicle, or when you need an occupational license to keep driving on a suspended license. A second DWI makes the device effectively mandatory, showing up at bond, at sentencing, and on probation. So the honest answer to how many DUIs require a car breathalyzer in Texas is that the count alone doesn’t decide it; the circumstances of even one arrest can.

One quick terminology note. Texas law calls adult drunk driving “driving while intoxicated” under Penal Code Section 49.04.¹ “DUI” in Texas technically applies only to minors. Most people use the terms interchangeably, and every rule below sits in the DWI statutes.

When a First DWI Triggers an Interlock

A standard first-offense DWI is a Class B misdemeanor, and the judge has discretion to order an IID as a condition of bond or probation but isn’t required to.¹ Many first-time offenders never see one.

Three situations change that, even on a first offense:

BAC of 0.15% or higher. This bumps the charge to a Class A misdemeanor, and judges routinely impose an IID as part of probation in high-BAC cases.¹
DWI with a child passenger. Driving while intoxicated with anyone under 15 in the vehicle is a state jail felony, even as a first offense. This charge is specifically listed in Article 17.441, meaning the magistrate must impose an IID as a condition of bond. A person with no prior DWI history can land under a mandatory interlock this way.²³
Occupational license applications. If your license was suspended after any DWI conviction and you apply for an occupational license to keep driving for work, school, or essential household needs, Transportation Code Section 521.246 requires the judge to restrict you to vehicles with an IID installed. The court can waive it only by specifically finding the device isn’t necessary for community safety and that waiving it serves the interest of justice.⁴

There’s one practical carve-out on that last point. If your job requires you to drive a vehicle your employer owns, and the employer has been notified of your restriction, you can operate that company vehicle without an IID installed. The employer can’t be a business you own or control.⁴

When a Second DWI Triggers an Interlock

With a second or subsequent DWI, Texas layers the IID requirement onto multiple stages of the case, so avoiding it at one point usually just means meeting it at the next.

As a Bond Condition

When you’re arrested for a second or subsequent DWI, the magistrate is required to order an ignition interlock as a condition of release on bond. You must install the device on your vehicle within 30 days of release, at your own expense. The magistrate can waive it only by specifically finding the restriction would not be in the best interest of justice.³ This same mandatory bond condition applies, regardless of prior DWI count, to intoxication assault, intoxication manslaughter, and DWI with a child passenger.

After Conviction

For a second or subsequent DWI conviction within five years of the previous offense, the court must order an IID on every vehicle you own or operate. The device has to stay installed until one year after your license suspension ends.⁵

On Probation

If a repeat DWI offender is placed on community supervision, an IID is mandatory for at least half of the supervision period under Code of Criminal Procedure Article 42A.408, and the judge can extend it.⁶ For first-time offenders on probation the IID is discretionary, though commonly ordered in high-BAC cases.

How Long the Device Stays Installed

Duration depends on which legal mechanism triggered the IID, and several can stack:

Bond condition: Until the case is resolved by dismissal, acquittal, or sentencing.
Probation condition: At least half of your community supervision period, with the judge able to order longer.⁶
Repeat conviction under Section 49.09(h): One year past the end of your license suspension.⁵
Occupational license: The full duration of the license suspension, unless the court finds good cause for earlier removal.⁴

The underlying suspensions under Section 521.344 run 90 days to one year for a first DWI, 180 days to two years for a repeat offense enhanced under 49.09(a) or (b), and one to two years for a repeat DWI subject to 49.09(h).⁷ A repeat offender convicted under 49.09(h) can realistically carry an IID for three years or more once the mandatory post-suspension year is added. The sentencing court keeps jurisdiction over you until the IID requirement expires.⁵

What the Device Costs

You pay for it yourself in almost every case. Typical Texas pricing runs roughly $70 to $150 for installation, $60 to $100 per month for the lease and data monitoring, and $50 to $100 for removal. A year on the device usually totals around $800 to $1,400 before removal.

If the court finds you genuinely can’t afford it, there are limited options. The occupational license statute lets the court set a payment schedule that can’t extend beyond twice the period of the order.⁴ Under the repeat-conviction provision in Section 49.09(h), a payment plan can’t exceed one year from installation.⁵

Violations and Tampering

The device logs every breath sample, every failed test, and every skipped retest. Courts receive those reports, so compliance problems surface quickly. What happens next depends on which IID order you violated:

Bond violation: The court can revoke your bond, triggering a warrant and jail time until the case resolves.
Probation violation: The state can move to revoke community supervision. If granted, you face the original jail or prison sentence.
Occupational license violation: Your restricted license can be suspended or revoked, leaving no legal way to drive.
Conviction order under 49.09(h): Noncompliance is punishable as contempt of court.⁵

Having someone else blow into the device, or physically tampering with it, can bring additional criminal charges on top of whatever your underlying IID order carries. Judges see these attempts routinely in the data logs and treat them as a serious aggravating factor at sentencing or revocation.

Getting the Device Removed Early

Texas allows early removal, but only with court approval. You generally need to have had the device installed for at least half of your probation or supervision period with a clean compliance record before a judge will consider it. The process requires filing a motion. If the judge grants it, you send a copy of the order to the Texas Department of Public Safety, which can take up to 21 days to process. The device can’t come off until DPS issues its official response.

Early removal is far from guaranteed. A single failed test or compliance issue during the required period can disqualify you, and most judges want to see an extended stretch of clean data before signing off.

1
State of Texas. Texas Penal Code Section 49.04 – Driving While Intoxicated
2
State of Texas. Texas Penal Code Section 49.045 – Driving While Intoxicated with Child Passenger
3
State of Texas. Texas Code of Criminal Procedure Article 17.441 – Conditions Requiring Motor Vehicle Ignition Interlock
4
State of Texas. Texas Transportation Code Section 521.246 – Ignition Interlock Device Requirement
5
State of Texas. Texas Penal Code Section 49.09 – Enhanced Offenses and Penalties
6
State of Texas. Texas Code of Criminal Procedure Article 42A.408 – Use of Ignition Interlock Device
7
State of Texas. Texas Transportation Code Section 521.344 – Suspension for Offense