PA Emissions Testing: The Second Sticker

Walking through a parking lot, you may have noticed that most cars have two stickers on the windshield. The first is for the state safety inspection; We covered the safety inspection and much of what it entails in a previous blog that you can read here. Today, we’ll look more into the second sticker: the Pennsylvania state emissions testing.

Who Needs It?

In short, most of us in this area need this test done. Emissions testing requirements are set by two main criteria: location and vehicle weight. The most populated areas of the state, concentrated around Harrisburg, Philadelphia and Pittsburgh, require emissions testing. Also, every vehicle with a gross weight rating of 9,000 pounds or less requires an emissions test. There are exceptions for classic, antique and other types of vehicles, but for most folks in these regions an emissions test is necessary. 

Why Do We Do It?

The goal of the emissions testing program is to ensure clean air by minimizing vehicle pollution. Manufacturers are required to follow guidelines for the amount of pollution a vehicle emits. After the sale, the vehicle is tested on an annual basis to ensure its emissions are kept within those limits.

What Happens During the Test?

There are two methods for emissions testing in Pennsylvania; The most common of which is OBD (on-board diagnostic) testing. The vehicle is connected to a state emission analyzer and run through a check of the vehicle’s computer. The analyzer will look to see that the check engine light is on or off. If the light is on, the vehicle fails the test and the condition causing the check engine light must be repaired. If the light is not on then the vehicle passes and a sticker is applied to the windshield to show it has passed the test.

Vehicles with a gross weight rating of 8,501-9,000 pounds are subject to a two-speed idle test. During this test, a probe is placed in the tail pipe to measure the levels of exhaust gas coming from the engine. The engine is run for a period of time both at idle and at 2,500 RPM and the measurements must stay below the maximum test limits. If the reading exceeds the test limit, repairs must be made to bring it into compliance. If it passes, a sticker is applied to the windshield.

Wait! I Wasn’t Ready!

The OBD test is a pass/fail test. If the check engine light is on, it fails. If the check engine light is not on it passes, but there are two stipulations to this. First, the check engine bulb has to work properly! The bulb cannot be covered up or removed to avoid the emissions test. When the ignition key is turned on, the bulb should light up for a few seconds and then go off. This is called a bulb check and every icon in the cluster will do this. Verifying a functional check engine light is part of the emissions test.

Second, the vehicle must be ready for the emissions test. As a vehicle is driven, and even when it’s turned off, the computer is constantly running tests on every part of the car. These tests are organized into groups called monitors, as each group of tests monitors a general area of the vehicle. As the computer runs and completes these tests the monitors will be flagged as ‘complete’ or ‘incomplete’.

When a check engine light is turned off, either with a scan tool or by disconnecting the battery, all of the monitors will become incomplete. At this time, the vehicle will not pass or fail the test because the results can’t be known! If it has not run all of the monitors it cannot record a fault and turn on the check engine light. It also cannot know that there are no faults because it has not been able to test for them.  

It takes several miles of driving under various conditions for the vehicle to run all of its tests and complete the monitors. The tests may require certain road speed, engine and ambient temperatures, run time, engine RPM and other conditions be met in order to run. It may also require a period of hours before the engine is started. Once the monitors are completed the emissions testing can be performed and a pass or fail result obtained.

What’s an Exemption?

Vehicles that have driven less than 5,000 miles in the previous year are issued an emission sticker but do not get tested. The mileage is recorded with state for reference next year. A vehicle can be exempt one year and require a test the next, all dependent on miles driven.

Can’t I Just Get the Safety Sticker?

One of the requirements for issuing the safety sticker is first passing the emissions test. Until the emissions test is passed a safety sticker will not be issued. Of course, if the vehicle does not require a test this rule does not apply.

Does BBack Perform Inspections?

Why, yes we do! We do both state safety and emissions testing for cars, trucks, motorcycles and trailers. Give us a call or request an appointment online to schedule your inspection.