Virtually all automobile exhaust systems checked by Northern Virginia inspection stations are passing the test on the first try, state police said yesterday.

A total of 5,230 vehicle inspections were made the first eight days of the program, which is required by state and federal law because air quality in Northern Virginia does not meet government standards.

All but 192, roughly 4 percent, passed the tests the first time, according to Sgt. John Bowden, who is in charge of the Virginia State Police inspection program for Northern Virginia.

Bowden said minor repair work brought most of the 192 vehicles that failed up to standards.

However, the owners of two cars spent $60 to $75 each trying to comply with emissions rules. When the cars still failed to pass, the owners were issued waivers. Virginia law says a motorist cannot be required to spend more than $75 for repairs to get his vehicle certified, Bowden said.

Police officials said the test can be done in about 10 minutes and costs $3.50. It is available at about 125 service stations and repair shops in Arlington, Alexandria, Fairfax County and Prince William County. More stations will be certified as soon as they install necessary equipment and meet other state requirements, police said.

"An inspection station can be found by looking for the emissions poster displayed in the station's front window," Bowden said.

Under the Virginia program, many motorists must have a receipt for the exhaust inspection to get new Virginia automobile tags, beginning this month. For those who have tags expiring Jan. 31, time is short. Others have tags that do not expire until next Dec. 31.

Maryland and the District of Columbia are to begin inspection programs in 1983.

Not all Virginia drivers are affected.

The state's law applies only to vehicles manufactured the last eight model years and registered in Arlington, Alexandria, Fairfax County, Prince William County, Fairfax City, Falls Church, Manassas or Manassas Park.

Diesel-powered vehicles and those weighing more than 6,000 pounds are excluded from the inspection requirements.

Some Virginia legislators opposed the inspection program because it begins a year earlier than those in surrounding jurisdictions, because it affects only Northern Virginia motorists and because the inspections can be done any time during the year.

The equipment for the emission inspections costs an average of $3,500, according to Bowden, who added the equipment must be approved by state police for accuracy.

During the inspection, the station attendant places a stainless steel probe in the vehicle's tailpipe while the motor is idling. The probe is connected by a rubber hose to an analyzer that measures hydrocarbon and carbon monoxide levels.

Bowden said that cars from the 1975 through 1979 model years must emit less than 600 parts per million hydrocarbon and less than 6 percent carbon monoxide. The standard for 1980 vehicles is 400 parts per million hydrocarbon and 4 percent carbon monoxide; for 1981 and later vehicles, it is 300 parts per million hydrocarbon and 3 percent carbon monoxide.

If the vehicle passes, an emissions inspection receipt will be placed in the lower left corner of the windshield and the owner will receive a receipt. If the vehicle fails, the owner will receive a rejection sticker and will need to repair the vehicle to reduce emissions to acceptable levels, Bowden said.

Motorists have up to 30 days to get the repairs done for a new inspection, although they may need to act faster if their auto tag due date comes first.

Bowden said each inspection station is required to have at least one mechanic who has passed an emissions inspection certification course and can perform necessary repairs to the exhaust system.

Motorists who have questions about the accuracy of the emissions test on their car can call the State Police hotline, 703-971-0856 for Arlington, Alexandria and Fairfax County and 703-369-0421 for Prince William County.