Carb Advisory Engine Inspection Requirements

To: Owners, Operators, Renters or Lessees of In-Use Off-Road Vehicles in California

Number 381

August 2008

Revised May 2011


Attention: California operators of work over rigs: Any vehicle licensed and registered by the California Department of Motor Vehicles (DMV) for on-highway use must have an on-road certified engine to propel the vehicle while on-highway. For more information regarding this requirement, refer to Health and Safety Code Sections 43009 and 43013. This requirement is strictly enforced, and penalties can be assessed.

Periodic Smoke Inspection Program

All 4-year old and older on-road licensed diesel fleet vehicles with a gross vehicle weight rating of 6,000 pounds or greater must be compliant with the Periodic Smoke Inspection Program (PSIP.) PSIP requires those vehicles to be tested annually with a smoke opacity meter, and the test records, repair information, and any post-repair tests to be maintained for at least two years. For more information see Enforcement Advisory 351 or visit .

How to Comply

In order to comply with the on-road certified engine requirements for on-road licensed diesel work over rigs, you will be given the opportunity to follow the accelerated replacement/repower requirements within the In-Use Off-Road Diesel Vehicles regulation. However, all new 2008 model year on-road licensed vehicles must have California Air Resources Board (CARB) on-road certified engines. For further information about the Off-road regulation, please visit our website at: . Fact sheets are available at , and the full text of the regulation is available at .

For questions regarding enforcement of the In-Use Off-Road Vehicle regulation, please contact the diesel vehicle information hotline at (866) 6-DIESEL or (866) 634-3735.

Engine Replacement and Repower Requirements

At the time of engine replacement or repower, if you continue to license and register the vehicle for on-road use, the replacement/repower engine must be CARB certified for on-road use. At the time of engine replacement/repower, if you choose not to replace/repower the engine with a CARB certified on-road engine, the on-road license and registration will be revoked. If this happens, you will need to tow or low-boy the vehicle from site to site, and comply with all applicable laws and permits.

The replacement engine must meet CARB on-road certification standards based on the current engine’s model year. For example, if the current engine is a model year 1998, the replacement engine must be a CARB certified on-road model year 1998 or newer model year. For more information on engine change guidelines, visit

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