Quick Answer
Quick Answer
Nevada checks tailpipe smoke, emissions parts, and the fuel cap. A diesel may fail if its smoke is too dense, a required part is missing or changed, or a part shows signs that it does not work. An improper or missing fuel cap can also affect the report. The result does not name the repair. A trained diesel repair tech must find the cause.
Diesel Smog Guide
Nevada Checks Smoke and Emissions Parts
The main test measures smoke from the tailpipe. The inspector also looks at the parts that control emissions.
The test applies to a diesel car or truck when it meets the state rules. The vehicle must have a maker's GVWR of 14,000 pounds or less. It must be a 1968 model or newer and be based in a covered part of Clark or Washoe County. New vehicles have a test break for their first three registrations.
The test does not use the same steps as a gas-car test. A diesel vehicle goes on a dynamometer. The drive wheels turn on rollers at a steady set speed and load. An opacity meter reads the smoke.
The inspector also checks the emissions parts and fuel cap. A vehicle can have a problem in one area even when another area looks fine.
Diesel Smog Guide
Why Nevada Uses Set Test Conditions
The vehicle must be at its normal operating temperature before the opacity check. The dynamometer then holds the drive wheels at a set speed and load. The meter reads the exhaust under that state process.
Smoke seen during a start or road trip does not set the state result. Nevada uses a set speed and load for the test. The test shows pass or fail. A repair tech must inspect the vehicle to find the cause.
Diesel Smog Guide
Dense Exhaust Smoke Can Cause a Failure
Opacity means how much light the exhaust smoke blocks. Clear air lets light pass. Dense smoke blocks more light.
The meter takes an exhaust sample while the test runs. Nevada sets a maximum level. A result over that level does not pass.
Many faults can raise smoke. A trained tech must test the vehicle before naming a bad part.
The color of smoke seen on the road does not replace the state test. A driver may notice smoke only under load. Another vehicle may smoke at idle. The opacity test gives the official smoke reading.
Do not treat a guess as a repair plan. Replacing parts without a test can waste money. It may also leave the real fault in place.
Diesel Smog Guide
Missing or Changed Emissions Parts Can Cause a Failure
The visual check is part of Nevada's diesel test. The inspector looks for the emissions parts listed on the maker's label.
A required part can fail the visual check if it is missing, changed, or shows signs that it does not work. The state calls it tampering when a change defeats an emissions control.
The maker's label matters because diesel systems can differ by engine and model. A part seen on a similar truck does not prove that both trucks use the same setup. The inspection is based on the equipment listed for the vehicle being tested.
For the same reason, a general parts list is a poor repair guide. A qualified diesel repair tech should inspect the exact vehicle and match the repair to its factory system.
Federal law bans making, selling, offering, or installing defeat parts. These parts stop an emissions system from doing its job. Nevada also bans the removal or change of required emissions parts. A test station cannot help hide those changes.
Keep the factory emissions system in place. If a prior owner changed it, have a repair shop restore the right parts before the retest. Nevada does not grant a waiver when required emissions parts are missing or changed.
The smoke and visual checks stand on their own. A passing smoke reading does not clear a missing or changed part. Having every required part does not clear an opacity reading over the state limit. The vehicle must pass each part of the inspection.
Diesel Smog Guide
A Fuel-Cap Problem Can Affect the Report
Nevada's light-duty diesel guide includes a fuel-cap check. A cap may be missing or may not work as it should.
If the cap is the only failed item, replace it with the right cap. Then take the failed report to an approved diesel station or a DMV Emission Control Lab for signoff. A new cap does not fix dense smoke or a missing emissions part.
The cap-only correction is not a waiver. It applies when the report shows that all other test areas passed. If the opacity or visual check also failed, the cap signoff does not clear those results.
Check the cap before the visit. It should be present and close as the maker designed. Use the right part for the vehicle.
Diesel Smog Guide
A Drive-System Limit Is Not a Smog Failure
The E Sahara & Atlantic station can test a RWD or 2WD diesel. It can also test selectable AWD or 4WD. A switch must put the vehicle into RWD or 2WD.
The station cannot test a full-time AWD vehicle that cannot be switched out of AWD.
If the drivetrain does not fit the rollers, the station cannot run the test or give a pass or fail result.
Check the owner's manual and drive controls before the visit. A four-wheel-drive badge may not show whether the vehicle has a two-wheel-drive mode.
Diesel Smog Guide
The Test Report Guides the Next Step
The test report shows the result. Keep it if the vehicle fails.
The report gives the repair tech a place to start. It may show an opacity failure, a visual issue, or a fuel-cap issue. The report does not prove that one named engine part caused the result.
A trained tech can test the engine and exhaust systems to find the cause of the failed result.
After the repair, the vehicle must take another state test. The test station measures the vehicle again. A repair bill does not replace the retest.
Do not ask a test tech to promise a pass. Nevada controls the test and the pass level. The vehicle must meet the standard when it returns.
Diesel Smog Guide
Nevada Has a Limited Waiver Process
Some diesel vehicles may qualify for a DMV waiver after they fail, receive repair work, and fail again. The Nevada DMV decides.
The owner must keep both failed reports and the repair receipts. The vehicle also goes to a DMV Emission Control Lab for review. A waiver is not certain.
The state sets rules for repair costs and receipt dates. Those amounts and steps can change. Follow the failed-test report and contact a DMV Emission Control Lab when a waiver may apply.
A vehicle does not qualify for that path when it failed because an emissions device is missing or was changed to defeat its job. A vehicle covered by a repair warranty may also be outside the waiver path.
A waiver may allow registration, but it does not repair the vehicle. A repair tech still needs to address the emissions fault.
Diesel Smog Guide
Get the Diesel Test at E Sahara & Atlantic
Smog Busters performs diesel smog checks at one Las Vegas shop. Go to E Sahara and Atlantic at 2711 E Sahara Ave.
The E Sahara & Atlantic diesel smog check page gives the correct address, map, and local service details. Other Smog Busters huts test gas vehicles but do not run the diesel test.
E Sahara & Atlantic runs the state diesel test. If the vehicle fails, take the report to a diesel repair shop. Make sure the shop works on diesel emissions systems.
The test report shows what happened during the inspection. A qualified diesel repair tech can trace the cause and explain the repair.
Diesel Smog Guide
Avoid Common Wrong Turns After a Failure
- Use the failed report before buying parts. The same result can come from more than one fault.
- Keep the factory emissions parts. Changing or removing them can cause a visual failure and a legal problem.
- Trust the opacity reading, not one puff of smoke. The meter sets the reading during the test.
- Return to E Sahara & Atlantic for the retest. Other Smog Busters huts do not run the diesel test.
- Keep the first report and repair papers. They help the repair tech, retest station, and DMV if a waiver review becomes an option.
Diesel Smog Guide
What to Do After a Failed Test
Keep the report and take it to a qualified diesel repair tech. After the legal repair, return to E Sahara & Atlantic for the state retest. The new test decides whether the vehicle passes.