Early state emission inspections (prior to 1996) were generally taken by inserting sensors into the tail pipe of the vehicle. These sensors, as crudes as they are, take samples from your engine exhaust very much like those sampled today by modern engine technology. The information is then relayed to the emission station computer and examined by a software program that generates results for a PASS or FAIL condition.
Pennsylvania adopted this inspection for all 1970  and newer vehicles. Vehicles that were produced before the 1970 mandate, were exempt.

Today your vehicle is equipped with an OBD data-port located somewhere inside the vehicle. Similar to the one shown here, these ports transmit engine information that has been collected by the vehicle on-board-computer. The technician plugs the emission interface directly into this port. The information retrieved is sent to the PENN-DOT receiving computer where your vehicle registration information is held in a database. The PASS or FAIL results remain in the database until such a time that this information is deleted. That would be, after you transfer, trade or sell the vehicle.
It is interesting to note that mileage and other items are also transmitted to DOT. You should be aware that any work done on the engine, such as replace sensors or OB computer, you must operate the vehicle for a set time before the data can be sent to the DOT computer.

The EMISSION PROGRAM as defined by Pennsylvania, is not required in all counties. If your vehicle is registered in any one of these counties, you may be exempt. You will also be exempt if you do not operate your vehicle for more than 5000 miles during any 12 month period. The rule only applies if you have owned the vehicle for that same period of time.

If you have any questions, please feel free to contact us...