Quick summary
- An ignition interlock device (IID) is a small breath tester wired into a car’s ignition that keeps the car from starting if it detects alcohol.
- In California, an IID is required after a repeat DUI or any DUI that caused injury, for 12 to 48 months depending on your record.
- After a first DUI with no injury, an IID is usually optional: it is one of three ways to keep driving, for up to 6 months.
- Driving without a required IID is a separate misdemeanor, punishable by up to 6 months in jail and a $5,000 fine.
- If your income is low, you pay only 10% to 90% of the device cost.
In this article, our California DUI defense lawyers answer 11 common questions about ignition interlock devices:
- 1. How long do I have to keep an IID?
- 2. First DUI: your three options
- 3. What if I drive without my interlock?
- 4. When does my IID time start and end?
- 5. DMV-only (APS) suspensions
- 6. Driving on a DUI-suspended license
- 7. How much does an IID cost?
- 8. Getting an IID installed
- 9. How does an IID work?
- 10. Can I fight a failed test?
- 11. Frequently asked questions
1. How long do I have to keep an IID?
How long you must keep an IID depends on two things: whether anyone was hurt, and how many prior DUIs you have in the last 10 years. These rules are in California Vehicle Code 23575.3, which was updated on January 1, 2026, and applies to DUIs committed on or after January 1, 2019.1
Required IID time by your record
Here is how long the law requires you to keep an IID:2
| Your record | DUI, no injury | DUI causing injury |
|---|---|---|
| No prior DUIs | Optional: up to 6 months if the court orders it | 12 months |
| 1 prior | 12 months | 24 months |
| 2 priors | 24 months | 36 months |
| 3 or more priors | 36 months | 36 months |
| A prior felony DUI | 36 months | 48 months |
Required IID terms in California by prior DUIs. A first DUI with no injury is the only case where the IID is optional.
What counts as a “prior”
A prior is an earlier conviction in the last 10 years for DUI, DUI causing injury or a “wet reckless” (a reckless driving plea in a DUI case).3 That is why a wet reckless plea can still matter later, even though it is not a DUI.
Every car you drive needs an IID
The IID must be in every vehicle you drive, not just the one you own. During your IID period you may not ride a motorcycle at all, because no IID has been certified for motorcycles.4
2. First DUI: your three options
After a first DUI with no injury and no priors, you get only one of these three options:5
Your three options after a first California DUI with no injury.
What the law says
If a judge orders an IID for a first DUI, the law caps it at 6 months:
“If the court orders the ignition interlock device restriction, the term shall be determined by the court for a period not to exceed six months from the date of conviction.”
— Vehicle Code 23575.3(h)(1)(A)(i)5
Which option is best for you?
The two IID options let you drive anywhere, while the third limits you to work and your DUI class. In our experience, most first-time clients who need to keep driving choose the DMV’s IID-restricted license, because it lets them get back to a normal routine right away. The right choice depends on your job, your commute and whether you can afford the device, so it is worth talking through with a lawyer before you decide.
3. What if I drive without my interlock?
If your license is restricted to IID-equipped cars, driving any car without a working IID is a separate crime under Vehicle Code 23247(e).
The penalty
“Any person convicted of a violation of this section shall be punished by imprisonment in a county jail for not more than six months or by a fine of not more than five thousand dollars ($5,000), or by both that fine and imprisonment.”
— Vehicle Code 23247(f)6
In plain terms, it is a misdemeanor with up to 6 months in jail and a fine of up to $5,000. If the IID was part of your DUI probation, it can also be a probation violation. A conviction also ends your IID-restricted license, and the DMV suspends or revokes your license again.6 In our experience, prosecutors are often willing to resolve a first violation without jail time when there was a real reason for it, such as an emergency, and the driver got back into compliance quickly. For more, see our page on penalties for driving without an interlock.
Asking someone else to blow into the device
It is also a misdemeanor to ask someone else to blow into your IID or start the car for you, and for that person to do it.7
Can I drive someone else’s car?
Only if it has a certified IID installed. The restriction follows you, not your car.
Work vehicles
You may drive an employer-owned vehicle for work without an IID if you have told your employer about the restriction and carry proof of that notice. This does not apply to a business you own or control.8
4. When does my IID time start and end?
Many drivers assume the clock starts on the day of their arrest or conviction. It usually does not.
When the time starts
Your IID time generally counts from when the DMV receives your proof of installation (form DL 920) and issues your IID-restricted license, not from your arrest or court date. The sooner you install the device and send in the form, the sooner your time starts running.
What can extend it
The installer must tell the DMV if:9
- the device is removed,
- it shows that you tried to remove, bypass or tamper with it, or
- you miss three or more required service appointments.
Any time you are out of compliance does not count toward your required IID period, so it effectively adds time to it.9 Removing, bypassing or tampering with an IID is also a separate crime.7
When your time is up
Don’t remove the device on your own when you think your time is up. Check with the DMV that your restriction has ended first, then have the installer remove it. Removing it early is reported to the DMV.
5. DMV-only (APS) suspensions
The DMV can suspend your license after a DUI arrest, even before (or without) a conviction. This is called an administrative per se (APS) suspension, meaning the DMV acts on its own, separate from the court case. For a first offense it lasts 4 months, and you can get an IID-restricted license right away for up to 4 months.10 To get it, you need to:
- Enroll in a DUI program,
- File proof of insurance (an SR-22 form from your insurer),
- Send the DMV proof of installation (form DL 920), and
- Pay a $125 APS fee.
6. Driving on a DUI-suspended license
If you are convicted of driving on a license suspended for DUI (Vehicle Code 14601.2, 14601.4 or 14601.5), the court must order an IID for 1 to 3 years, depending on your prior DUI and suspended-license convictions in the last 10 years.11
7. How much does an IID cost?
The device
As of November 2026, providers’ published California prices run about $99 to $116 a month to lease the device, or a little under $3 a day, plus $50 to $150 to install it. Ask about calibration and removal fees before you sign. See our guide to ignition interlock costs for more.
DMV fees
The DMV charges its own fees, as of November 2026:12
- $103 administrative fee when a mandatory IID term applies,
- $125 for an IID restriction after an APS suspension, and
- license reissue ($55) and restriction ($15) fees.
Help paying for the device
If your household income is at or below 400% of the federal poverty level, you pay only part of the provider’s standard program cost:13
| Your income (share of federal poverty level) | You pay |
|---|---|
| 100% or less | 10% |
| 101% to 200% | 25% |
| 201% to 300% (or receiving CalFresh) | 50% |
| 301% to 400% | 90% |
You must show the provider proof of income. Costs caused by not following the program rules are not reduced.
What about Vehicle Code 23700?
Vehicle Code 23700 set up California’s earlier IID pilot program in Alameda, Los Angeles, Sacramento and Tulare counties for offenses from July 2010 through December 2018. Today’s rules, including the income-based cost share, are in Vehicle Code 23575.3.12
8. Getting an IID installed
Finding a certified installer
Installers must be licensed in California. The DMV directs drivers to the Department of Consumer Affairs license search to confirm an installer is licensed.12
The paperwork
- Have the IID installed in every car you will drive.
- Get the “Verification of Installation” (form DL 920) from the installer and send it to the DMV.
- Enroll in your DUI program and file an SR-22 insurance form.
- Pay the DMV fees above.
Servicing every 60 days
Each IID must be checked and calibrated by the installer at least once every 60 days.9
Exemptions
- No car: if you don’t own or have access to a vehicle, you can be exempt until you get one, but you must certify this to the DMV within 30 days of its notice.14 See Do I need an interlock if I don’t own a car? and our page on the declaration of non-ownership.
- Medical reasons: you can ask for an exemption on DMV form DL 4063.12
- Drug-only first offense: a first DUI involving only drugs, with no injury, may be exempt from the IID requirement.12
Exempt drivers must still serve the full suspension and finish a DUI program.12
9. How does an IID work?
An IID is a small breath-alcohol tester wired into your car’s ignition. Before the car will start, you blow into it. If it detects alcohol above its set limit, the car will not start.
You must give an alcohol-free breath sample before the car will start, and again at random while you drive.
Random retests while you drive
While you drive, the device asks for random “rolling” retests, typically a few minutes after you start and then periodically, with several minutes to respond so you can pull over safely. A failed or missed retest will not shut off a running car, but it is recorded and reported.
What the device records
The device logs every test, every engine start and stop, and any attempt to disconnect or tamper with it.
10. Can I fight a failed test?
Yes. A failed or missed test is not proof that you drove after drinking.
Common causes of false readings
Most IIDs use fuel-cell sensors that react to alcohol, not to smoke, perfume or gasoline. But any alcohol in your mouth will register, including from:
- alcohol-based mouthwash and breath sprays,
- liquor-filled candy, and
- some yeasty pastries and bread.
Mouth alcohol fades within minutes, so rinse with water, wait and test again.
Using the device’s own records
In our experience, the device’s own log is often the best defense: a failed test followed minutes later by a clean retest points to mouth alcohol, not drinking. Calibration and service records can also show that a device was not working properly. If you get a violation notice, keep receipts and write down what you ate or used, then talk to a lawyer before you respond.
11. Frequently asked questions
Is an IID required for a first DUI in California?
Not usually. For a first DUI with no injury, the court may order an IID for up to 6 months, or you may choose the DMV’s IID-restricted license, but it is one of three options. An IID is required for 12 months after a first DUI that caused injury.
What is the penalty for driving without an interlock?
Up to 6 months in county jail and a fine of up to $5,000, plus a possible probation violation.
Can I drive a different car without an IID?
No. If your license is restricted to IID-equipped vehicles, every car you drive must have a certified IID, with a limited exception for an employer’s vehicle used for work.
How long do I have to keep an IID after a second DUI?
12 months for a second DUI with no injury, or 24 months if someone was injured.
What is Vehicle Code 23700?
It created California’s 2010–2018 IID pilot program in four counties. Today’s IID rules are in Vehicle Code 23575.3.
What is form DL 920?
The “Verification of Installation” your IID installer fills out so you can prove to the DMV that the device is installed.
Call us for help
If you or a loved one is facing a DUI and has questions about an ignition interlock device, our California DUI attorneys offer free consultations. Call us or fill out the form on this page to talk through your options.
Legal references:
- California Vehicle Code 23575.3: (p) “The requirements of this section shall apply only to a person who is convicted for a violation of Section 23152 or 23153 that occurred on or after January 1, 2019.” (Amended by Stats. 2025, Ch. 689 (AB 366), effective January 1, 2026; repealed as of January 1, 2033, unless extended.)
- California Vehicle Code 23575.3(h): (h)(1)(B) “Upon a conviction with one prior, punishable under Section 23540, the person shall install a functioning, certified ignition interlock device in the vehicle, as ordered by the court, that is operated by that person for a mandatory term of 12 months.” Terms of 24 and 36 months follow for two and three or more priors, and 12, 24, 36 and 48 months for DUI causing injury (h)(2).
- California Vehicle Code 23575.3(h)(3): “Prior” includes a conviction under Section 23103 as specified in Section 23103.5 (wet reckless), or Section 23152 or 23153.
- California Vehicle Code 23575.3: “Vehicle” does not include a motorcycle until the state certifies an ignition interlock device that can be installed on a motorcycle. A person subject to an ignition interlock device restriction shall not operate a motorcycle for the duration of the ignition interlock device restriction period.
- California Vehicle Code 23575.3(h)(1)(A): Upon a first conviction with no priors, “only one of the following may occur”: a court-ordered IID for up to six months, a restricted license under Section 13352.4, or an IID-restricted license under Section 13352(a)(1).
- California Vehicle Code 23247(e)–(f): (e) “It is unlawful for any person whose driving privilege is restricted pursuant to Section 13352, 13352.1, 13353.6, 13353.75, 23575, 23575.3, or 23700 to operate any vehicle not equipped with a functioning ignition interlock device.” (g)(1): on a conviction under (e), the department “shall immediately terminate the restriction and shall suspend or revoke the person’s driving privilege for the remaining period of the originating suspension or revocation”; (g)(2) provides for suspension of a person restricted under Section 23575.3.
- California Vehicle Code 23247(b)–(d): Unlawful to request or solicit another person to blow into an ignition interlock device or start a vehicle equipped with one for a restricted driver, and unlawful to do so for that driver. (d) “It is unlawful to remove, bypass, or tamper with, an ignition interlock device.”
- California Vehicle Code 23576: Employer-owned vehicle exception; does not apply to a vehicle owned by a business entity all or partly owned or controlled by the restricted person.
- California Vehicle Code 23575.3: Each vehicle must be serviced by the installer at least once every 60 days; the installer notifies the department if the device is removed or tampered with, or if the person fails three or more times to comply with maintenance or calibration requirements. (j) “[T]he period in which the person was not in compliance shall not be credited towards the mandatory term for which the ignition interlock device is required to be installed.”
- California DMV, “DUI First Offenders: Alcohol Involved, Non-Injury, 21 and Older”: APS: 4-month suspension; IID-restricted license available immediately for up to 4 months with DUI program enrollment, SR-22, form DL 920 and a $125 APS fee.
- California Vehicle Code 23573(j): IID for one, two or three years after a conviction under Section 14601.2, 14601.4 or 14601.5, depending on prior convictions within 10 years.
- California DMV, Statewide Ignition Interlock Device Program: Fees ($103 administrative service fee; $125 for alcohol-related APS IID restrictions), the income-based cost share (10%, 25%, 50%, 90%), license reissue ($55) and restriction ($15) fees as listed in the DMV first-offender guide, certified installers, exemptions (forms DL 4062 and DL 4063), and the 2010–2018 four-county pilot.
- California Vehicle Code 23575.3: Income at 100% of the federal poverty level or below: 10% of program costs; 101% to 200%: 25%; 201% to 300%: 50%.
- California Vehicle Code 23575.3(d)(2): Exempt until the person purchases or has access to a vehicle, if within 30 days of notification the person certifies to the department that they do not own or have access to a vehicle.