If your diesel motorhome is registered in California and has a gross vehicle weight rating (GVWR) over 14,000 pounds, California’s diesel motorhome smog requirements put it under the California Air Resources Board’s Clean Truck Check program, with an annual test tied to your DMV registration renewal date and a 2026 compliance fee of $32.13.1California Air Resources Board. Clean Truck Check Compliance Fee Update Effective 1/1/2026 Lighter diesel motorhomes follow a different path, and out-of-state rigs are left alone entirely.
Which Program Your Motorhome Falls Under
California runs two separate emissions programs, and weight decides which one applies to your coach.
Diesel motorhomes with a GVWR over 14,000 pounds are exempt from the Bureau of Automotive Repair (BAR) Smog Check Program and instead fall under CARB’s Clean Truck Check.2Bureau of Automotive Repair. Smog Check Manual There is no model-year cutoff for Clean Truck Check: a 1990 diesel pusher and a brand-new Class A are both in the program as long as the GVWR exceeds 14,000 pounds and the motorhome is registered in California.3California Air Resources Board. Clean Truck Check – FAQ
Diesel motorhomes at or below 14,000 pounds GVWR go the other direction. If the coach is model year 1998 or newer, it goes through the standard BAR smog check like a passenger car.4Bureau of Automotive Repair. Smog Check – When You Need One and Whats Required Model year 1997 and older at or below that weight is exempt from BAR too.
Your GVWR is the maximum allowable loaded weight of the vehicle. Look for it on the manufacturer’s label on the driver’s-side door jamb. If that sticker is missing, the number is on the title documents.
A few categories fall out of Clean Truck Check regardless of weight. Zero-emission vehicles (fully electric or hydrogen) are not subject to the program. Neither are military tactical vehicles as defined under Title 13 of the California Code of Regulations. And motorhomes registered in another state are exempt even while traveling California roads for personal recreation, an exemption specific to motorhomes and not shared by commercial trucks from out of state.3California Air Resources Board. Clean Truck Check – FAQ Register that motorhome in California, though, and the exemption disappears.
Everything below applies to the heavier rigs, over 14,000 pounds GVWR and California-registered.
What You Owe Each Year
Motorhomes used for personal recreation or emergency occupancy are on an annual schedule, not the semi-annual cycle CARB uses for commercial trucks.5California Air Resources Board. Clean Truck Check – Emissions Compliance Testing Requirements The compliance deadline is your DMV registration renewal date.6California Air Resources Board. Clean Truck Check – Motorhome Fact Sheet
Three things have to happen before that date:
- Report the vehicle in the Clean Truck Check Vehicle Inspection System (CTC-VIS) at cleantruckcheck.arb.ca.gov.
- Pay the annual compliance fee. For 2026 it is $32.13, up from $31.18 in 2025 based on consumer price index changes.1California Air Resources Board. Clean Truck Check Compliance Fee Update Effective 1/1/2026
- Submit a passing emissions compliance test from a CARB-credentialed tester.7California Air Resources Board. Clean Truck Check – Overview Fact Sheet
You can submit a passing test result up to 90 days before your compliance deadline.8California Air Resources Board. Clean Truck Check Periodic Testing Requirements Starting early is worth it on older rigs, where a first-try failure is more likely. CTC-VIS will send notifications every 30 days beginning 90 days out.
How the Emissions Test Works
What your motorhome actually goes through depends on the engine’s model year, not the year of the coach. A 2010 motorhome that was repowered with a 2015 engine follows the newer path.
Engines Model Year 2013 and Newer
A CARB-credentialed tester connects a certified diagnostic device to the engine’s on-board diagnostic (OBD) port. To pass, the engine needs no active diagnostic trouble codes, and its emissions monitors have to be in a “ready” state, with no more than two OBD monitors incomplete and enough driving activity since any codes were last cleared.9California Air Resources Board. Clean Truck Check – On-Board Diagnostic (OBD) Readiness Criteria
A common trap: a shop fixes an emissions issue, clears the codes, and sends the owner straight to the tester. The engine has not driven enough for its monitors to reset, so the result comes back “Not Ready,” which is not a pass. Drive the motorhome for a while after any repair before you retest.
Engines Model Year 2012 and Older
Older diesels without OBD capability go through a two-part inspection. The tester runs a snap-acceleration smoke opacity test using a SAE J1667-compatible smoke meter, rapidly accelerating the engine while the meter reads how much light the exhaust smoke blocks.3California Air Resources Board. Clean Truck Check – FAQ With a diesel particulate filter (DPF) installed, the opacity limit is 5%. Without a DPF, the limit is 40%.10California Air Resources Board. Clean Truck Check – Opacity Testing Guide
Then comes a visual inspection of the emissions control equipment: EGR system, catalytic converter, aftertreatment devices.5California Air Resources Board. Clean Truck Check – Emissions Compliance Testing Requirements Removed, bypassed, or tampered-with equipment is an automatic failure regardless of the opacity reading.
Where to Get Tested and What It Costs
Only CARB-credentialed testers can perform Clean Truck Check inspections and submit results. A regular BAR smog station cannot do this test. CARB publishes a public list of credentialed testers available for hire, searchable through CTC-VIS.11California Air Resources Board. Clean Truck Check – Available for Hire Credentialed Testers Many testers are mobile and will come to your storage location, which helps for coaches that are awkward to drive across town. Expect roughly $50 to $90 for the test itself, on top of the $32.13 CARB fee.
If You Fail or Miss the Deadline
A failed test or a missed compliance deadline triggers an SB 210 registration hold, blocking most DMV transactions until the motorhome is compliant.12California Air Resources Board. Clean Truck Check – CA DMV Registration Hold (SB 210) You cannot renew your registration. Driving the rig anyway invites a citation from the California Highway Patrol and stacked late-registration penalties from the DMV.
When the motorhome fails, the tester’s report identifies the reason: a high opacity reading, an active diagnostic trouble code, or missing emissions equipment. Repair the underlying issue and retest. Testing 60 to 90 days before your deadline gives you room to fix problems and submit a passing result on time.
The DMV’s late-registration surcharges compound the problem. They start at 10% of the vehicle license fee at 1 to 10 days late and climb to 160% of the license fee after two years.13California DMV. Registration Fee Penalties License fees on a heavy diesel motorhome are not small, so those percentages add up. CARB also has independent authority to cite operators of non-compliant vehicles under the Heavy-Duty Inspection and Maintenance regulation, though for personal motorhome owners the registration block is the enforcement mechanism you are most likely to encounter.
One note on financial help: the Bureau of Automotive Repair’s Consumer Assistance Program covers vehicles in the BAR Smog Check system, and diesel motorhomes over 14,000 pounds GVWR are exempt from that system. Whether CAP extends to Clean Truck Check vehicles is not confirmed in CARB or BAR materials, so don’t plan around it.
Buying, Selling, or Moving to California
When a diesel motorhome over 14,000 pounds GVWR changes hands, the seller’s Clean Truck Check compliance can transfer to the buyer, but only if the vehicle met all compliance requirements within 90 days before the transfer date.3California Air Resources Board. Clean Truck Check – FAQ Otherwise, the buyer inherits the obligation.
If you’re buying, check the motorhome’s compliance status in CTC-VIS before you close. A non-compliant coach will carry a registration hold, and you’ll be paying for emissions repairs and testing before the DMV will put the title in your name. If you’re selling, a passing test within the last 90 days makes the transfer smooth. The regular used-car smog certificate does not apply to these heavier diesel motorhomes, because they are exempt from the BAR program.2Bureau of Automotive Repair. Smog Check Manual Clean Truck Check is the standard.
Moving to California with a diesel motorhome? The DMV requires registration within 20 days of establishing residency or bringing the vehicle into the state.14California DMV. New to California Once it’s registered here, Clean Truck Check applies. You can report the vehicle in CTC-VIS even with a temporary plate while you wait for permanent ones.7California Air Resources Board. Clean Truck Check – Overview Fact Sheet Book a credentialed tester soon after registration. An engine that passed elsewhere may still miss California’s opacity limits or OBD readiness rules, and finding that out early beats finding it out the week your registration is due.