Whether your RV needs a smog check in California comes down to three things: fuel type, gross vehicle weight rating (GVWR), and model year. Most gasoline motorhomes follow the same biennial Smog Check rules as passenger cars. Diesel and other non-gasoline motorhomes over 14,000 pounds skip the Smog Check program entirely and fall under the California Air Resources Board’s Clean Truck Check instead. Getting the category wrong can land you with a DMV registration hold, so it is worth confirming which program applies before your renewal comes due.
Gasoline, Hybrid, and LPG Motorhomes
Gasoline, hybrid, and liquefied petroleum gas motorhomes follow the standard Smog Check rules regardless of size or weight. The Bureau of Automotive Repair splits them into three groups by model year:1Bureau of Automotive Repair. Smog Check: When You Need One and What’s Required
- 1975 and older: fully exempt. No testing, no fee.
- Eight model years old or newer: exempt from the biennial inspection. You pay a smog abatement fee with your DMV renewal instead.
- 1976 through eight model years old: biennial Smog Check required for registration renewal.
The eight-year window rolls forward each year. A 2019 motorhome, for example, stays exempt through 2026 and needs its first biennial Smog Check in 2027.
Diesel Motorhomes at 14,000 Pounds or Less
Lighter diesel RVs are in the regular Smog Check program only if they are 1998 model year or newer and have a GVWR of 14,000 pounds or less.2California DMV. Smog Inspections Diesel RVs from 1997 and older are exempt. If your diesel falls in the 1998-and-newer group under the weight cap, it goes through the same biennial inspection schedule as a gasoline RV at a licensed Smog Check station.
Diesel and Alt-Fuel Motorhomes Over 14,000 Pounds: Clean Truck Check
This is where many RV owners get caught off guard. If your motorhome runs on diesel or any fuel other than gasoline and its GVWR is over 14,000 pounds, it does not go through Smog Check at all, regardless of model year. It falls under CARB’s Clean Truck Check program.3California Air Resources Board. California Motorhomes: Get Ready for Clean Truck Check A large share of Class A diesel motorhomes exceed 14,000 pounds, so this covers more owners than most people expect.
Clean Truck Check has three ongoing obligations:4California Air Resources Board. Clean Truck Check – Motorhome Fact Sheet
- Register the vehicle in CARB’s Clean Truck Check Vehicle Inspection System (CTC-VIS).
- Pay the annual compliance fee, which is $31.18 as of January 2025 and adjusts for inflation.5California Air Resources Board. Clean Truck Check Compliance Fee Update Effective 1/1/25
- Have a CARB-credentialed tester perform annual emissions testing. Motorhomes with 2013 or newer diesel engines get an OBD scan; those with 2012 or earlier engines need a smoke opacity test and a visual inspection of emissions equipment.
Clean Truck Check testing is not done at a regular Smog Check station. You need a CARB-credentialed tester, found through CARB’s website. The DMV is actively placing registration holds on vehicles that are not compliant.6California Air Resources Board. Clean Truck Check – Overview Fact Sheet
One boundary worth knowing: motorhomes registered outside California are not subject to Clean Truck Check even if they drive through the state.6California Air Resources Board. Clean Truck Check – Overview Fact Sheet
When Testing Is Required Beyond Renewal
Besides biennial renewal, a Smog Check is required when you sell or transfer the motorhome and when you first register an out-of-state RV in California.7California Legislative Information. California Vehicle Code 4000.1 The seller is responsible for providing a valid certificate on sale, though gasoline motorhomes four model years old or newer are exempt from the transfer requirement. Transfers between a parent, grandparent, sibling, child, grandchild, or spouse are also exempt. A Smog Check certificate is valid for 90 days, so complete your registration or sale within that window to avoid retesting.1Bureau of Automotive Repair. Smog Check: When You Need One and What’s Required
California does not apply Smog Check uniformly. Enhanced and basic program areas require biennial inspections; more rural change-of-ownership areas only require a Smog Check at sale, transfer, or initial California registration.8Bureau of Automotive Repair. Smog Check Reference Guide 2025 Your DMV renewal notice will say whether an inspection is required for your specific period.
A practical note for Class A and larger Class C owners: many standard Smog Check bays are built for sedans and SUVs. Call ahead to confirm the station can physically fit your motorhome. Some stations specialize in larger vehicles.
What It Costs
Private stations set their own Smog Check prices, typically in the range of $40 to $90, plus a state certificate fee of $8.25. Stations in enhanced areas running a dynamometer test sometimes charge more than those doing a simple OBD scan. If your RV is in the eight-model-year exemption window, you pay a smog abatement fee with your DMV renewal in place of an inspection charge.2California DMV. Smog Inspections
If Your RV Fails
A failed Smog Check means emissions repairs and a retest before the DMV will process your renewal. The Bureau of Automotive Repair’s Consumer Assistance Program (CAP) offers help to income-qualified owners.9Bureau of Automotive Repair. Consumer Assistance Program
Repair Assistance
Households at or below 225% of the federal poverty level can apply for repair assistance covering emissions work at a CAP-authorized facility.10Bureau of Automotive Repair. Income Eligibility Requirement The program pays up to $1,450 for 1996 and newer vehicles and up to $1,100 for 1976 through 1995 models.11Bureau of Automotive Repair. Apply for Repair Assistance
Repair Cost Waiver
If repairs still do not get your RV to pass, income-eligible owners can obtain a repair cost waiver that allows two-year registration without a passing certificate, provided you have spent at least $650 on qualifying emissions repairs at a licensed station.12Legal Information Institute. California Code of Regulations Title 16 3340.43 – Repair Cost Limit Diagnostics count toward the total; the cost of the smog test itself does not.
Vehicle Retirement Rarely Applies to RVs
CAP also pays owners to permanently scrap a vehicle: $1,500 or $2,000 for income-eligible owners, $1,350 for anyone regardless of income. The catch for RV owners is the eligibility limit. Retirement is restricted to passenger vehicles, trucks, SUVs, and vans with a GVWR of 10,000 pounds or less.13Bureau of Automotive Repair. Retire Your Vehicle Most motorhomes exceed that weight, so the retirement route is realistically closed to the majority of RVs that fail.