The Nevada smog check, explained

The program has a handful of moving parts: where it applies, which vehicles it covers, what kind of test a vehicle gets, and what happens after the result. Here is the whole thing in one place, built from the Nevada DMV's own pages, with links to the deeper pages on this site for each piece.

At a glance

• Required only in the urban parts of Washoe and Clark counties (Nevada DMV).
• 1968 and newer gasoline vehicles at any weight, and diesels up to 14,000 lb GVWR.
• 1996 and newer light-duty vehicles get the plug-in OBD II test; older and heavy-duty vehicles get a tailpipe test.
• A pass is valid 90 days (180 days on a Nevada dealer sale) and is sent to the DMV in real time.

Where Nevada tests

The requirement is not statewide. It follows where a vehicle is based: the urban areas of Washoe County and Clark County. In Washoe that is Reno, Sparks, Washoe Valley, most of the area west of Washoe Valley and everything in the county south of the 40th parallel. Incline Village, Crystal Bay, Sutcliffe, Nixon and Wadsworth are named as exempt.

In Clark County it is the Las Vegas Valley and a five-mile buffer around it. Vehicles based in every other Nevada county are exempt. Our testing area guide goes place by place for the Reno side.

Which vehicles are covered

Inside a testing area, the rule covers gasoline vehicles of any weight and diesels with a manufacturer's gross vehicle weight rating of 14,000 pounds or less, model year 1968 and newer. The test is due every year at registration renewal.

The exempt list is specific. New vehicles skip their first three registrations. Hybrids skip their first five model years. Electric vehicles, vehicles running only on propane, CNG, methane or butane, motorcycles and mopeds, 1967 and older vehicles, diesels over 14,000 pounds, replica vehicles and qualifying classic plates under 5,000 miles a year are all exempt, along with a few kinds of ownership transfer.

The three kinds of test

The model year and the fuel decide how a vehicle is tested.

• OBD II plug-in test: 1996 and newer light-duty vehicles. The technician scans the VIN, plugs the analyzer into the diagnostic port under the dash and reads the car's own computer. The DMV says most of these take five minutes or less. See how the OBD test works.
• Two-speed tailpipe test: vehicles built in 1995 or earlier and all heavy-duty vehicles. See the tailpipe test page.
• Light-duty diesel test: a dynamometer test, an opacity test of the exhaust and a visual inspection of the emission components. See diesel rules.

Pass, fail or not ready

A pass goes to the DMV electronically right away, so you can renew online through MyDMV, at a DMV Now kiosk, or at a station that offers renewal. It stays valid for 90 days.

A fail comes with a report that says why. On a 1996 or newer car, a lit check engine light is an automatic fail. The vehicle has to be repaired and pass a retest before it can be registered, and if it still fails after qualifying repairs, it may be eligible for a waiver. Our failed smog check page lays out the order of steps.

A rejected result, often shown as not ready, is different from a fail. It means the car's computer has not finished its self-checks, usually after a battery was disconnected or codes were cleared. The DMV's advice is to drive for up to a week in mixed city and highway driving and come back; no repair is needed.

Timing your test

You can renew about 35 days before the registration expires, and a pass lasts 90 days, so testing a few weeks ahead is the comfortable window. The DMV's own tip is to test early: if something turns up, there is time to fix it before the deadline. Nevada has no grace period on an expired registration, though a short movement permit is available while repairs are underway.

What it costs

The DMV sets a yearly maximum fee for each county from a survey of labor rates, and every station sets its own price at or under that cap. Stations must post their fees. For the current figures, see our price and fees page, or call either location for today's price.