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Heavy Duty Diesel Smog Checks

Hensley's Auto Does Heavy Duty Diesel Smogs. Mobile service avalible for 3 vehicles or more.  Otherwise you will need to come in.  Please detatch trailer before comming in.


Vehicles with an OBD system are 2013 and above in most cases. OBD vehicles will have a check engine light or some kind of MIL for the emisson system. 


There is no visual inspection on heavy duty 14,000 gvwr vehicles getting an OBD smog check.   Gas vehicles require a visual inspection.  There is no guidence on monitor set critera like there is for gas vehicles.  

Vehicles without an OBD system will require an opacity test.  An opacity test checks for particulate matter.  These vehicles will require a visual inspection.  An emission sticker is required otherwise the vehicle will fail the test.  If you don't have an emssion sticker you will need to contact the engine manufacturer to get one. 

Heavy Duty Diesel Roll Out Dates

     Starting January 1st 2023 Roadside Emissions Monitoring Devices (REMD) will be placed on CA roads in order to flag vehicles who have high emissions.

      If your vehicle is flagged you will get a Notice to Submit to Testing (NST) letter and have 30 days to submit a passing emissions test to CARB.

Starting 7/1/2023

Vehicle owner is required to add there vehicle to the clean truck database and pay a $30 fee.

Tutorial for clean truck database

Registration link for clean truck database

Starting in 2024 14,000 gvwr  duty diesel vehicles will need to be smoged 2 times a year that have an OBD system (On Board Diagnostics) Generaly that is 2013 and newer vehicles.  Those vehicles will have a check engine light also.  


Heavy duty recreational vehicles will be smogged 1 time per year.

Starting in 2027 the inspection interval will be increased to 4 times per year for obd systems.  Recreational vehicles will remain 1 time per year.

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