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Guardian vs Smart Start

Your state's approved list decides first: in most states you can only choose from the companies on it. Where both are approved, the device, the service centers near you and the fees are what differ.

Guardian logoGuardianGuardian AMS 2500 (name from NM directory; site names no model)16 of 44 state lists
Smart Start logoSmart StartSSI-20/3040 of 44 state listsApp Store 2.0 from 113 ratings

Where each one is approved

AlabamaAlaskaArizonaColoradoFloridaGeorgiaIndianaKansasMaineMassachusettsMinnesotaNew JerseyNorth CarolinaNorth DakotaOklahomaPennsylvaniaSouth DakotaTexasWyomingConnecticutMissouriWest VirginiaIllinoisNew MexicoArkansasCaliforniaDelawareDistrict of ColumbiaHawaiiIowaKentuckyMarylandMichiganMississippiMontanaNew HampshireNew YorkOhioOregonTennesseeUtahVirginiaWashingtonWisconsinNebraskaSouth CarolinaIdahoNevadaVermontLouisianaRhode Island
BothOnly GuardianOnly Smart StartNeitherNo list we could read
Both 15

Arkansas, California, Colorado, Georgia, Idaho, Indiana, Kentucky, Maryland, Massachusetts, Nebraska, Nevada, New Jersey, Oklahoma, Rhode Island, Texas

Only Guardian 1

Vermont

Only Smart Start 25

Alabama, Alaska, Arizona, Connecticut, Delaware, District of Columbia, Florida, Hawaii, Illinois, Iowa, Kansas, Maine, Minnesota, Missouri, New Hampshire, North Carolina, Ohio, Oregon, South Carolina, Tennessee, Utah, Virginia, Washington, Wisconsin, Wyoming

Guardian vs Smart Start: the devices

GuardianSmart Start
SensorFuel cell. Guardian says the device uses fuel cell alcohol-specific technology.1Alcohol-specific fuel cell sensor.2
Warm-upGuardian gives no warm-up figure. It says you may see a slightly longer warm-up during extreme cold.3Not published
Operating temperatureGuardian says accuracy exceeds NHTSA specifications of -40° to 180° F. This is a marketing claim.4Not published
Size and weightGuardian says the handset is similar in size and shape to a cell phone, and it is removable. No weight is given.5Smart Start says it is no bigger than the average smartphone.6
MotorcyclesGuardian says it does not install its device on motorcycles.7Smart Start says the device is compatible with most motorcycles.8
How you blowNot publishedBlow and hum for 3 to 4 seconds. Some states use blow-inhale-blow, and the pattern depends on your state.9
CameraNot publishedOptional, and whether it is required depends on your state.10
GPSNot publishedOptional.11
Real-time reportingNot publishedOptional.12
Rolling retest windowNot published5 minutes to respond once prompted, per a 2017 Kansas manual. Smart Start's current rules may differ.13
Electric and hybrid carsNot publishedSmart Start says the device is compatible with most electric vehicles.8
AppNot publishedThe free Smart Start Client Portal app handles account management.14

Guardian vs Smart Start fees

FeeGuardianSmart Start
Monthly lease$50-$120/monthNational15from $1.99/dayNational, varies by state. Smart Start advertises no long-term contract.16
Installation$0 total upfrontColorado, New Mexico and California only17$150.00Filed in New York18
CalibrationNot published$25.00Filed in New York19
RemovalNot published$94.99Filed in New York20
Lockout or violation resetNot published$80.00Filed in New York21
Missed appointmentNot published$55.00Filed in New York. Not charged with 24 hours notice.22
Closing or admin feeNot published$69.50Filed in New York23
Enrollment or set-up$0 total upfrontColorado, New Mexico and California only17$40.00Filed in New York24

In Texas

GuardianSmart Start
Certified service centers10144
Advertised~$3/dayfrom $1.99/day*
Installfreefrom $150

Texas DPS service center list; prices advertised Oct 23, 2026. Texas interlock guide

InterlockCompare is independent and isn't affiliated with either company. Not legal advice.

Sources 24 sources from 4 sites, including guardianinterlock.com, smartstartinc.com, ksrevenue.govShow

Every fact on this page comes from one of these.

  1. The Guardian IID features cutting-edge fuel cell alcohol-specific technologyguardianinterlock.com/guardian-ignition-interlock-device
  2. Alcohol-specific fuel cell technology Yes Yes Yessmartstartinc.com/about-us
  3. you may see a slightly longer warm-up period during extreme coldguardianinterlock.com/support/faq
  4. Accuracy exceeds NHTSA specifications (-40° to 180° F)guardianinterlock.com/guardian-ignition-interlock-device
  5. similar in size and shape to a cellular phoneguardianinterlock.com/support/faq
  6. no bigger than the average smartphonesmartstartinc.com/ignition-interlock-devices/best-ignition-interlock
  7. No, we do not install our device on motorcyclesguardianinterlock.com/support/faq
  8. compatible with most electric vehicles, motorcycles, and other vehicle typessmartstartinc.com/ignition-interlock-devices/best-ignition-interlock
  9. Blow into the device for three or four seconds while humming at the same timesmartstartinc.com/ignition-interlock-devices
  10. Optional camera for positive identification Yes Yessmartstartinc.com/about-us
  11. Optional GPS tracking Yes Yes Yessmartstartinc.com/about-us
  12. Optional real-time reporting Yes Yes Yessmartstartinc.com/about-us
  13. Once prompted for a retest, you have 5 minutes toksrevenue.gov/doviidmanuals/SmartStart.pdf
  14. downloading our free Smart Start Client Portal appsmartstartinc.com/ignition-interlock-devices/cost
  15. Leasing an ignition interlock device generally costs between $50-$120 per monthguardianinterlock.com/ignition-interlock-pricing
  16. From $1.99/Day* - No Long-Term Contractssmartstartinc.com
  17. Offer valid in Colorado, New Mexico, and California onlyguardianinterlock.com/ignition-interlock-pricing
  18. Install Vehicle Model >5 Years Old*criminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  19. Calibration, Inspection, Monitoring Fee*criminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  20. Removal Fee*criminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  21. Service Lockout Feecriminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  22. Missed Appointment Feecriminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  23. Administrative Closing Feecriminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf
  24. Enrollment Feecriminaljustice.ny.gov/opca/pdfs/Smart Start- NY State Pricing Schedule 04242025.pdf