How Long Does A Smog Check Take?

Smog checks or emissions tests are mandatory procedures done to verify if a vehicle meets a state’s prescribed emissions standards. New to emissions tests? You might be wondering “How long does an emissions test take?”

You should probably allot 20 to 30 minutes for a smog check. That said, you can finish an emissions test in as fast as 10 to 15 minutes.  You should also anticipate the possibility of queues, especially during peak times. If you can, try to go on a weekday afternoon to save time.

This might sound quick, but if your vehicle fails the smog test, then you’ll need to make the necessary adjustments, modifications, or repairs, which will take more time. Most emissions test centers will give you an emissions report that indicates whether you’ve passed or failed the smog test. If you’ve failed the smog test, you’ll have to pay a diagnostic fee to diagnose your vehicle.

If you own a vehicle that’s made from the year 2000 or newer, you’ll get a cheaper diagnostic fee. The fee is generally more expensive when it comes to older vehicles. Additionally, diagnosing a vehicle after failing a tailpipe emissions test is typically more expensive than a failed test from seeing a check engine light.

Emissions Test Steps

An emissions test isn’t as simple as inserting a tube into your vehicle’s exhaust and revving the engine. After filling up the forms, the first thing a mechanic will do is check if your emissions control system is functioning as it should. These include the catalytic converter, the exhaust gas recirculation (EGR) system, and evaporative control system, among other components.

The mechanic will also check your vehicle’s gas cap if it’s properly sealed, since a leaking gas cap can cause fuel vapors to leak, which is a form of emission itself. The mechanic will also check your vehicle’s ignition timing using a specialized tool.

They will also check your vehicle’s check engine light. If this light is illuminated, then it means that your vehicle’s onboard diagnostic (OBD) system has detected an issue, which will immediately cause you to fail the test. Make sure you don’t have an illuminated check engine light before getting an emissions test. If you do, make sure to resolve the issue causing your vehicle’s check engine light to illuminate.

The emissions test will also check the OBD system’s readiness monitor and determine if it’s ready for an emissions test. An OBD system’s readiness monitor is the vehicle’s self-diagnostics. Some tests are conducted regularly when the vehicle is operating. However, other diagnostics require the vehicle to meet specific conditions. For a vehicle made after the year 2000, its readiness monitors for all its vehicle systems except its evaporative emissions system (EVAP) monitor need to be ready before an emissions test is conducted.

The emissions test also checks the OBD system’s readiness monitor. Depending on the vehicle’s year, there are specific limits. For instance, vehicles from ’96 to ’99 are allowed to have one readiness monitor not ready, which could be any of them. From 2000 onwards, only the EVAP monitor is allowed to be not ready; all other monitors must be ready.

–Anthony Harlin, ASE Certified Master Automobile Technician

The emissions test personnel will then connect a scan tool to your vehicle’s OBD data link connector, which is typically underneath the steering wheel. This allows a computer to scan the vehicle’s OBD system. 

The vehicle’s OBD system can typically detect if the engine has faulty oxygen sensors or other issues. If the scan tool detects that the OBD system has stored codes because of faulty components, then your vehicle is most likely not performing within specification and will cause your vehicle to fail the test. 

The data link connector also checks various systems like the EVAP system, ignition timing, and exhaust gas recirculation system, among others. In some states, this is as far as the smog test goes. In other states, however, your vehicle will still need to go through a tailpipe test where a hose is inserted into its exhaust. Vehicles made before 1996 and vehicles that don’t have OBD systems are required to conduct a tailpipe test. 

This process typically involves revving the engine for a few seconds while a computer analyzes your vehicle’s exhaust gases. Sometimes, the personnel will make you drive on a dynamometer during this procedure. The emissions personnel will also inspect the underside of your vehicle for fuel leaks. 

Once your test is finished, you’ll receive a Vehicle Inspection Report. The testing station will also electronically transfer the test information to your local Department of Motor Vehicles (DMV) so you can register your vehicle.

Why Are Smog Checks Important?

The Federal government is vowing to halve the country’s total emissions by 2030 as a response to climate change. The US has been the leading country when it comes to greenhouse gases for many years now. Aside from switching to electric and hybrid vehicles, part of its strategy includes having stricter emissions standards across all vehicle classes.

Where to Buy New EVAP System Parts

To ensure your vehicle passes the emissions tests, you’ll want to make sure its EVAP system is in tip-top shape. If it fails the tests, you’ll need to repair the problematic parts anyway, and you’ll need to go through the hassle of re-testing before you can proceed with registration. Best get repairs out of the way early by purchasing replacement parts at CarParts.com.

The CarParts.com catalog includes a wide range of quality aftermarket parts from trusted manufacturers. We even offer these parts at various price points to suit different budgets. We can’t overstate the convenience of ordering so many of your replacement EVAP parts from one source. Our parts will ship to your door in as fast as two business days too, meaning you don’t need to wait long if your emissions test is right around the corner.

Don’t wait until the last minute to prep your vehicle for its emissions test. Order a brand new canister purge solenoid or other replacement EVAP system parts at CarParts.com now.