What is an Ignition Interlock Device (IID)?

An IID is a small device (about the size of a cell phone) and wired to your vehicle’s ignition that monitors alcohol-levels of the driver. After installation, the IID requires your breath sample before the engine will start. If the IID detects alcohol on your breath, the engine will not start. As you drive, you are periodically required to provide breath samples to ensure the continued absence of alcohol in your system. IIDs are increasing in popularity as a California DUI penalty from both the court and the DMV.

How Do IIDs Work?

As previously stated, an ignition interlock device is a type of mini-breathalyzer instrument.  About the size of a cell phone, it is installed on the steering column of your car.

If the judge orders you to install an IID as part of your California DUI probation, you must:

  1. have the IID professionally installed, and
  2. have an IID installed in every car you own or drive. (Employer-owned cars and motorcycles are exempt from this rule.)

Before you start your car, you must blow into the IID and provide an alcohol-free breath sample.  If you don’t, your car will not start.  Once you are driving, the IID will ask for random samples, between 5-15 minutes after you begin driving and then about every 45 minutes thereafter.

When the instrument asks for these “rolling” samples, you have six minutes to provide a sample–plenty of time to pull over if you don’t feel that you can safely provide a sample while driving.

If you don’t “pass”, your ignition interlock device will not disable your car. The IID will, however, register a “fail” on your log that gets reported to the court.

It must be noted that California ignition interlock devices are designed to ensure that only you as the driver can provide your own breath sample.  This is accomplished by:

  • requiring a specific breath pattern for the sample,
  • having a very short cord that will not reach to the passenger or back seats,

requiring random samples, even while driving, and

  • making it a crime to ask someone else to fraudulently provide his/her sample in lieu of yours.4
  • In addition, the technology of California IIDs is so advanced that the IID detects and records:
    • any attempts to disconnect or tamper with the device,
    • all engine starts and stops, and
    • all breath test results.

Once you have installed a California IID, you must take it in for servicing at least every 60 days.

Will I Have to Install an IID If I Am Convicted of California DUI?

A judge may order you to install a California ignition interlock device (IID) for:

  • a first offense of violatingVehicle Code 23152(a) VC driving under the influence, especially if the defendant’s BAC of .015% or higher,
    • a first offense of refusing to submit to a chemical blood or breath test,
  • a first offense of violating Vehicle Code 23152(b) VC driving with a blood alcohol concentration (BAC) of 0.08% or greater, or
  • Vehicle Code 14601 VC suspended license violationsstemming from DUI convictions.

Meanwhile, a judge will order you to install an IID for

  • repeat DUI convictions, or
  • Vehicle Code 23153 VC DUI causing injury.

In addition to situations where a judge may require you to install an ignition interlock device, there are a number of DUI conviction scenarios where a judge must require you to install an IID. An experienced attorney will be more informed. Each case is different.

First-time DUI offenses 

The length of time that a first-time DUI defendant may be required to keep an IID in their car following conviction is usually 6 months. (If the defendant does not get convicted of DUI but is found liable by the DMV, the mandatory period of the suspension (which is usually 6 months).

If DMV has found you guilty and your license is suspended, you may be eligible for an IID if you have:

  1. Signed up for DUI school (at least a 3-month program)
  2. Obtained Special Insurance (SR – 22) for drivers who have received a DUI(s)

Repeat DUI offenses  

Under California law, a criminal judge must order you to install a California IID for a period of:

  • one (1) year following a second DUI conviction,
  • two (2) years following a third DUI conviction and
  • three (3) years following a fourth or subsequent conviction.
  • And if you are convicted of a second DUI causing injury, you must install the IID for two (2) years (three years for a third conviction).

(If the defendant does not get convicted of DUI but is found liable by the DMV, the mandatory period for having an IID is usually just one year, no matter whether it’s a second or third conviction.)

The following table summarizes the required period of IID installation:

Type of DUI Conviction Period of Mandatory IID Installation (if the driver wants to continue driving during the license suspension period)
VC 23152(a) or 23152(b): first offense 6 months
VC 23152(a) or 23152(b): second offense 1 year
VC 23152(a) or 23152(b): third offense 2 years
VC 23152(a) or 23152(b): fourth or subsequent offense 3 years
VC 23153 DUI causing injury: first offense 1 year
VC 23153 DUI causing injury: second offense 2 years
VC 23153 DUI causing injury: third offense 3 years


Mandatory IID for VC 14601 driving on a suspended license

There are requirements for IID installation following one or more convictions for Vehicle Code 14601 driving on a suspended license when the suspension / revocation was based on a DUI conviction.

Depending on the exact license violation–and on how many prior DUI and/or suspended license violations you have suffered–the judge may order you to install an IID for one (1) to three (3) years.

How Much Does a California Ignition Interlock Device Cost?

On average, the cost of a California IID is about $2.50 per day.  Some companies additionally charge around $75-$100 for installation.  You may also be required to pay fees for maintenance and calibration of your ignition interlock device.

Under California’s mandatory IID pilot program law (Vehicle Code 23700 VC), if you can’t afford the cost of your mandatory IID, you will only be required to pay a portion of the costs.

How Do I find a Court-Approved IID Installer?

If a California court requires you to install an ignition interlock device on your car, you must go to an authorized installer to have it done. Several private companies are approved by the courts.

IID installation companies you may want to consider include:

Court-Ordered IID Restriction

When the court orders the use of an IID, you must have one installed by an authorized installer and provide proof of installation to the court. The court has special forms and procedures to monitor drivers ordered to have an IID installed. After the Department of Motor Vehicles (DMV) is notified by the court, DMV places a restriction on your driver license (DL) and marks your driving record so law enforcement officers are aware of the IID requirement if you are stopped. If you fail to comply with a court-ordered IID restriction, the court will notify DMV and your driving privilege may be suspended until you comply with the court order.

DMV-Ordered IID Restriction

DMV is required to impose an IID restriction on your driving privilege when you are convicted of driving with a suspended or revoked DL for a driving under the influence (DUI) conviction (California Vehicle Code (CVC) §§14601.2, 14601.4, or 14601.5).

This restriction does not allow you to drive without a valid DL.

You must submit either a Verification of Installation Ignition Interlock (DL 920) or Exemption for Ignition Interlock Device (DL 4054B) form to DMV within 30 days from the date the Order of Installment of an Ignition Interlock Device (DL 4054A) form was mailed. These forms ensure that you and the installer agree to the terms of the IID restriction.

Optional DMV IID

Restriction Requirements

If you were convicted of a DUI (CVC §§23152 or 23153) or “wet reckless,” (CVC §23103.5) you may be eligible for an IID-restricted DL. In addition to any other specified restriction requirements, you must meet the following requirements:

  • Clear all other outstanding suspensions/revocations on your driving record.
  • Comply with a DUI program’s requirements and have the program provider submit  the appropriate Proof of Enrollment Certificate (DL 107) or Notice of Completion Certificate (DL 101) form to DMV (whichever applies to your case).
  • Submit to DMV a California Insurance Proof Certificate (SR 22) form issued by your auto insurance company that establishes proof of financial responsibility.
  • Install an IID on your vehicle and provide DMV with a DL 920.
  • Pay all required fees.

IID Providers 

A list of DMV-certified IID manufacturer contact information is available at www.dmv.ca.gov.

Check the License of an IID Installer

All IID installation facilities doing business in California are required to have a valid license issued by the Bureau of Automotive Repair (BAR) or the Bureau of Electronic and Appliance Repair, Home Furnishings and Thermal Insulation (BEARHFTI), which are part of the Department of Consumer Affairs (DCA). To ensure that an IID installer is properly licensed, see the BAR website at www.dca.ca.gov.

IID Calibration and Monitoring

Once installed in your vehicle, the IID must be calibrated and inspected by a certified installer at intervals not to exceed 60 days. Your installer ensures the device is working properly and that no violations, such as failing to take random retests, have been logged. Noncompliance with IID requirements are reported to the court or DMV (whichever applies) and you may have your driving privilege suspended or revoked.

Certain violations require DMV to immediately suspend or revoke your driving privilege if you have an optional IID restriction (for example, an attempt to remove, tamper with, bypass, or failure to comply with any requirement for IID maintenance or calibration). DMV may restore the IID-restricted driving privilege upon receipt of a new DL 920.