What an interlock device is and why California requires it
An interlock device (also called an ignition interlock or IID) is a breath-testing machine wired into your vehicle's ignition system. Before the engine will start, you blow into the device. If it detects alcohol above a set limit — usually 0.02% blood alcohol content — the engine will not turn over. You must install one if you are convicted of driving under the influence (DUI) in California and your license is suspended as a result.
California law requires an interlock device for most DUI convictions, even first offenses. The device stays in your vehicle for a court-ordered period, typically 6 months to 3 years depending on the severity of your case and whether you have prior DUI convictions. During this time, you cannot drive any vehicle without the device installed.
The interlock requirement is separate from your license suspension. You may be suspended for a set number of months, but the interlock period often runs longer. This means you could regain driving privileges before the interlock period ends — but you still cannot legally drive without the device in place.
Key Takeaways
- California requires an interlock device for most DUI convictions, starting when ready after arrest or as ordered by the court.
- You must install the device in any vehicle you own or regularly drive, and you cannot operate that vehicle without it.
- The device costs money to install, calibrate, and monitor monthly — fees typically range from $60 to $150 per month depending on the provider.
- Tampering with, removing, or circumventing the device is a separate criminal offense and will extend your suspension and interlock period.
- You can request removal of the device only after your court-ordered period ends and you file paperwork with the DMV proving compliance.
When the interlock requirement begins
The timing depends on whether you are arrested before or after conviction. If you are arrested for DUI, California law allows the court to order an interlock device when ready — even before trial or conviction. This is called a pre-conviction interlock order. You may be required to install it within days of your arrest as a condition of bail or release.
If you are convicted, the court will order the device as part of your sentence. The order specifies the exact start date, usually the date of conviction or sentencing. You must have the device installed by the date the court sets, or you face additional charges for non-compliance.
Some courts allow a short grace period — typically 7 to 14 days — to locate a certified installer and schedule the installation. Do not assume you have time. Contact a certified interlock provider in California when ready after your arrest or conviction to confirm the important date and book an appointment.
Finding a certified installer and understanding the costs
You must use an interlock provider certified by the California Department of Justice. You cannot install an aftermarket device yourself or use an uncertified company. The DMV maintains a list of certified providers on its website, organized by county. Call ahead to confirm they serve your area and can meet your installation important date.
Installation typically costs $100 to $300 upfront, depending on the provider and your vehicle type. Monthly monitoring and calibration fees range from $60 to $150. Some providers charge extra for rolling retests — breath tests you must perform while driving to prove you remain sober. You are responsible for all costs; the court does not cover them.
If cost is a barrier, some providers offer payment plans. Ask about this when you call. You may also be able to request a fee waiver from the court if you can demonstrate financial hardship, though this is not may provide. Failure to pay does not suspend your obligation — you must still maintain the device or face additional penalties.
What you must do while the device is installed
Once the interlock is active, you have specific responsibilities. You must submit to breath tests whenever the device prompts you — typically at startup and at random intervals while driving. Refusing a test or failing one (registering above the set limit) is recorded by the device and reported to the court or DMV.
You must also attend monthly calibration appointments with your provider. These appointments may support the device is functioning correctly and allow the provider to read data from the device showing your test results. Missing a calibration appointment can result in a violation report sent to the court.
You cannot drive anyone else's vehicle, even temporarily, unless that vehicle also has an interlock device installed. You cannot borrow a friend's car, rent a vehicle, or drive a company car without first having the device installed in that vehicle. This applies to all vehicles you own or regularly operate.
What happens if you violate the interlock requirement
Violations include failing a breath test, tampering with or removing the device, missing a calibration appointment, or driving a vehicle without the device installed. Each violation is reported to the court or DMV and can result in serious consequences.
A single failed breath test may not trigger when ready action, but multiple failures or a pattern of violations will. The court may extend your interlock period by 6 months to 1 year, increase your fines, or add jail time to your sentence. Tampering with or removing the device is a separate criminal offense — a misdemeanor that can result in additional charges, fines, and jail time.
Driving a vehicle without the required interlock device is also a separate violation. If you are stopped by law enforcement and the device is not installed, you can be cited, arrested, and charged with violating the terms of your DUI sentence. Your license suspension will be extended, and you may face additional criminal charges.
How to remove the device and restore full driving privileges
You cannot remove the interlock device yourself or have anyone else remove it. Only a certified provider can remove it, and only after your court-ordered period has ended. The removal process involves the provider uninstalling the device and providing you with a removal certificate.
After the device is removed, you must file paperwork with the California DMV to restore your full driving privileges. You will need the removal certificate from your provider and proof that you completed the interlock period without major violations. Submit these documents to your local DMV office or by mail to the address listed on your suspension notice.
The DMV will review your file and, if everything is in order, will reinstate your license. This process typically takes 2 to 4 weeks. During this time, you may still be required to have the interlock device in your vehicle until the DMV officially confirms your reinstatement. Do not remove the device before receiving written confirmation from the DMV.
Frequently Asked Questions
Can I drive someone else's car if they do not have an interlock device?
No. California law prohibits you from operating any vehicle without the required interlock device installed, regardless of who owns it. This includes borrowing a friend's car, renting a vehicle, or driving a company vehicle. Every vehicle you operate must have the device.
What if I cannot afford the monthly fees?
Contact your interlock provider about payment plans — many offer them. You can also request a fee waiver from the court by filing a motion and providing proof of financial hardship. However, inability to pay does not remove your obligation to maintain the device. Failure to pay will result in violation reports.
Does the interlock period end when my license suspension ends?
Not always. Your license suspension and interlock period are separate. You may regain driving privileges before the interlock period ends, but you must still keep the device installed until the court-ordered period is complete. Check your court order for the exact end date of your interlock requirement.
What if I move to another state while the device is still required?
You must maintain the interlock device in California until your court-ordered period ends, even if you relocate. Some states recognize California's interlock orders, but you should contact the DMV in your new state to confirm. Removing the device early or failing to maintain it while out of state is still a violation of your California sentence.
Can I get the interlock requirement removed early?
In rare cases, yes. You can petition the court for early removal if you can demonstrate exceptional compliance and changed circumstances. This requires filing a formal motion with the court that sentenced you and presenting evidence of your rehabilitation. Most courts deny these requests, but it is an option if your situation has significantly improved.