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Emissions Testing

Vehicles registered in Cache County with model years less than six years old are not required to have an emission test. Vehicles six years old and greater that have even- numbered model years must have an emission test in even-numbered years, and vehicles that have odd-numbered model years must have an emission test in odd-numbered years.


  • New vehicles with an MSO

  • Any vehicle with a model year 1968 & Older

  • Implement of husbandry (Farm) vehicles

  • Any vehicle used for maintenance or construction and not designed or licensed to operate on the highway

  • Any motorcycle or motor driven cycle

  • Electric vehicles

  • Tactical military vehicles

  • Any vintage or custom vehicle

  • Off highway vehicles

  • Any vehicle less than six years old

  • Any diesel vehicle 1997 & older or with a GVWR greater than 14,000 lbs.

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Why did I fail Emissions?

Vehicles equipped with On Board Diagnostic II (OBDII) self-test their emission system utilizing various monitors. Vehicles perform up to 11 system tests, depending on year, make, and model of the vehicle. These tests are commonly referred to as “readiness monitors.” The readiness monitors identify whether the vehicle’s computer has completed the required tests while the vehicle is being driven.

If a test has been completed, the system status will be reported “ready.” An uncompleted test will be reported “not ready.” An OBDII vehicle will not pass the annual inspection unless the required monitors are “ready.” The Vehicle Inspection Report from the test equipment will identify monitors that are not ready.


The Test equipment reads the OBDII and readiness monitor status as part of the vehicle’s emissions inspection. The vehicle inspector cannot change the information reported by the vehicle.

What Causes a “Not-Ready” Failed

  • Recent vehicle repairs in which diagnostic trouble codes have been cleared with OBDII scan tool; or

  • If the battery had been recently disconnected or replaced; or,

  • If the vehicle’s computer requires a software update; or, 

  • A pending problem has not yet illuminated the “check engine” light

How do I do a Generic Drive Cycle?


The purpose of the OBDII drive cycle is to run your vehicle’s onboard diagnostics. This, in turn, allows monitors to operate and detect potential malfunctions of your vehicle’s emission system. The correct drive cycle for your vehicle can vary greatly, depending on the vehicle model and the monitors that need to be reset. When a specific drive cycle is not known, or drive cycle information is not available from an owner’s manual, the generic cycle described below may assist with resetting your vehicle’s monitors. However, this generic cycle may not work for all vehicles.

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