As of 2014, Maryland requires a vehicle-safety-inspection certificate to register, sell or transfer most used vehicles. Some counties also require that most vehicles undergo an emission inspection every two years, although a number of vehicle types are exempt from this requirement, such as those with diesel engines.
Before a vehicle can be sold, it's first necessary to take it to a licensed inspection station to obtain an official certificate. The inspection normally takes approximately 1 1/2 hours; the price varies, depending on the service station's hourly-labor charges. As of 2014, there are approximately 1,600 stations throughout Maryland that the State Police has licensed to perform these vehicle safety inspections.
If the vehicle fails the inspection, the owner must have whatever problems the inspection identified fixed. The owner can hire whomever he or she wishes to complete the repairs, but the same mechanic needs to re-inspect the vehicle, regardless of who performed the repairs.
If the owner has the repairs completed within 30 days and has driven the car less than 1,000 miles since the original inspection, then only the issues identified by the mechanic need to be re-inspected. If it has been over 30 days or the car has more than 1,000 new miles, then the mechanic must re-inspect the entire vehicle.