Whether your RV needs a smog check in California comes down to three things: fuel type, model year, and gross vehicle weight rating (GVWR). Most gasoline motorhomes get a biennial Smog Check through the Bureau of Automotive Repair, lighter diesel RVs follow a similar schedule with a narrower model-year range, and heavier non-gasoline motorhomes go through a separate California Air Resources Board program called Clean Truck Check. Getting the category wrong can result in a DMV registration hold, so the distinctions matter.
Gasoline, Hybrid, and LPG Motorhomes
Gasoline, hybrid, and liquefied petroleum gas motorhomes follow the same Smog Check rules as passenger cars, regardless of size or weight. The Bureau of Automotive Repair sorts them by model year:1Bureau of Automotive Repair. Smog Check: When You Need One and What’s Required
- 1975 and older are fully exempt. No testing, no fee.
- Vehicles eight model years old or newer are exempt from the biennial inspection but pay a smog abatement fee at registration renewal.
- Vehicles from 1976 through eight model years old need a biennial Smog Check to renew registration.
The eight-year window is rolling. A 2019 motorhome, for instance, stays exempt through 2026 and would need its first biennial inspection in 2027. On a sale or transfer, the eight-year exemption shrinks: only gasoline motorhomes four model years old or newer skip the smog requirement at change of ownership.2California Legislative Information. California Vehicle Code 4000.1
Diesel Motorhomes at 14,000 Pounds GVWR or Less
Lighter diesel motorhomes fall under the traditional Smog Check program, but only if the model year is 1998 or newer.3California DMV. Smog Inspections Diesel RVs from 1997 and older are exempt. If your diesel motorhome is 1998 or newer and its GVWR is 14,000 pounds or less, you’re on the same biennial schedule as a gasoline RV, and the inspection looks the same.
Diesel and Alternative-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 has a GVWR over 14,000 pounds, it does not go through the regular Smog Check program at all. It falls under CARB’s Clean Truck Check, regardless of model year.4California Air Resources Board. California Motorhomes: Get Ready for Clean Truck Check A large share of Class A diesel motorhomes exceed the 14,000-pound threshold, so this applies to more RV owners than you might expect.
Clean Truck Check has three ongoing pieces:5California Air Resources Board. Clean Truck Check – Motorhome Fact Sheet
- Register the vehicle in CARB’s Clean Truck Check Vehicle Inspection System (CTC-VIS).
- Pay an annual compliance fee, set at $31.18 as of January 2025 and adjusted for inflation.6California Air Resources Board. Clean Truck Check Compliance Fee Update Effective 1/1/25
- Get an annual emissions test from a CARB-credentialed tester. Motorhomes with 2013 or newer diesel engines get an OBD scan. Motorhomes with 2012 or earlier engines get 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’ll need a CARB-credentialed tester, and CARB publishes a search tool for locating one. The DMV is actively placing registration holds on vehicles that aren’t compliant with the program, so skipping it isn’t a realistic option.7California Air Resources Board. Clean Truck Check – Overview Fact Sheet
One boundary worth naming: motorhomes registered outside California aren’t subject to Clean Truck Check, even when they drive through the state.7California Air Resources Board. Clean Truck Check – Overview Fact Sheet
What the Traditional Smog Check Involves
For motorhomes in the regular Smog Check program, the inspection combines a visual check that emissions equipment is present and connected, a functional check of items like the check engine light and evaporative controls, and either an OBD-II scan or a tailpipe test.8Justia Law. California Health and Safety Code 44010-44025 – Program Requirements For 2000 and newer RVs, the OBD-II scan is the core of the test. Motorhomes from 1976 through 1999 also get a tailpipe emissions test, with the specific procedure depending on your area.9Bureau of Automotive Repair. Smog Check Reference Guide 2025
The practical problem for RV owners is fit. Many Smog Check bays are built for sedans and SUVs. If you have a Class A or a larger Class C, call ahead to confirm the station can accommodate your motorhome; some stations specialize in bigger vehicles.
When You Need the Inspection
Your DMV renewal notice tells you whether a Smog Check is required for that registration period. Beyond biennial renewals, an inspection is also required when you sell or transfer the motorhome (the seller must provide a valid certificate) and when you first register an out-of-state RV in California.2California Legislative Information. California Vehicle Code 4000.1 Transfers between a parent, grandparent, sibling, child, grandchild, or spouse are exempt from the change-of-ownership smog requirement. A Smog Check certificate is good for 90 days, so you’ll want to complete the registration or sale inside that window to avoid a retest.1Bureau of Automotive Repair. Smog Check: When You Need One and What’s Required
What It Costs
Stations set their own inspection prices, typically in the range of $40 to $90, plus a state certificate fee of $8.25. Stations with dynamometer equipment sometimes charge more than those running a simple OBD scan. If your RV is in the eight-model-year exempt group, you’ll pay a smog abatement fee with your DMV registration renewal in place of an inspection.3California DMV. Smog Inspections
If Your RV Fails
A failed Smog Check means you’ll need emissions-related repairs and a retest before the DMV will process your registration. The Bureau of Automotive Repair runs the Consumer Assistance Program (CAP) for owners who qualify by income.10Bureau of Automotive Repair. Consumer Assistance Program
Repair Assistance
If your household income is at or below 225% of the federal poverty level, you can apply for repair assistance at a CAP-authorized facility.11Bureau 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.12Bureau of Automotive Repair. Apply for Repair Assistance
Repair Cost Waiver
If the RV still won’t pass after repairs, income-eligible owners can apply for a repair cost waiver, which allows registration for two years without a passing certificate provided at least $650 has been spent on qualifying emissions repairs at a licensed station.13Legal Information Institute. California Code of Regulations Title 16 3340.43 – Repair Cost Limit Diagnostics count toward the $650; the smog test itself does not. The threshold is adjusted biennially against the Consumer Price Index and has held at $650 for several years.
Vehicle Retirement Is Off the Table for Most Motorhomes
CAP’s retirement option pays owners to scrap a failing vehicle instead of repairing it, but it’s limited to passenger vehicles, trucks, SUVs, and vans with a GVWR of 10,000 pounds or less.14Bureau of Automotive Repair. Retire Your Vehicle Most motorhomes exceed that weight, so retirement is realistically unavailable for the majority of RVs that fail a Smog Check.