The Pennsylvania Department of Transportation requires annual safety inspections for all passenger cars. The goal of the safety inspection program is to ensure that vehicles are maintained for safe operation, preventing injuries or fatalities because of car failures. In addition to the safety inspection, PennDOT also requires annual emission tests. Only after passing both emission and safety inspections can a vehicle registration be renewed. Otherwise, you'll have to repair the issues with the car before you can renew your registration.
TL;DR (Too Long; Didn't Read)
Under Pennsylvania law, you must get a vehicle safety inspection and emissions test every year. Failure to do so will result in fines as well as inability to renew your registration.
Authorized Inspection Stations
PennDOT maintains a network of local businesses, repair shops and garages, authorized to perform safety inspections. Only certified mechanics of these authorized stations are allowed to perform safety inspections. Inspection fees are posted at each inspection station and do not include fees related with any eventual repair required to pass the inspection.
Safety Inspection Checklist
Auto safety inspections cover suspension components, steering, braking systems, tires and wheels, lighting and electrical systems, glass, mirrors, windshield washer, defroster, wipers, fuel systems, speedometer, odometer, exhaust systems, horns and warning devices, vehicle body, and chassis. A visual anti-tampering check, aimed at making sure the required emissions components have not been tampered with or removed, will also be performed.
Updated Inspection Sticker
Upon passing the safety inspection, PennDOT issues a sticker valid for a year from the month of inspection. Owners are required to display the sticker on the right-hand side of the windshield. Pennsylvania doesn't require that the date of the inspection sticker expiration and the date of the vehicle registration expiration match. To avoid a fine, the inspection sticker should not be allowed to expire for more than 30 days. If the vehicle owner is out of state for more than 30 days from the expiration of the inspection sticker, an extra 10 day grace period after his return is granted upon providing proof of absence.