The District of Columbia plans to begin annual auto pollution tests for Washington's 225,000 cars next January, as required by the federal Clean Air Act. But while the tests will be mandatory in 1982, motorists will not be required to make any repairs on cars that fail the tests until 1983.

The District, Virginia, Maryland and two dozen other states with the nation's worst air pollution are preparing vehicle inspection and maintenance programs despite rumors that the Reagan administration and the new Congress may scrap or change the programs when the 1970 Clean Air Act comes up for renewal this spring.

California and Kentucky, which have refused to go along with the federal auto emissions test program, last month were told by the Environmental protection Agency that they will lose about $900 million in federal funds during the next two years for failing to abide by the law.

New Jersey, Arizona and Oregon, which began their own state auto emissions test programs, have found they have reduced air pollution and that the average costs to motorists to repair cars that fail to tests is generally under $35, according to Tom Cackette, a top official with the EPA's Mobile Source Air Pollution Division in Ann Arbor, Mich.

Under the program, the District will inspect cars for excessive exhaust pollution with exhaust analyzers when vehicles are brought in for annual safety inspections. The city expects to charge $2 in addition to the current $3 safety inspection fee to cover the costs of the tests, according to Bob Kozak, the D.C. Department of Transportation official who is setting up the city's program. The city's costs will include hiring two additional inspectors and purchasing six to eight analyzers, which cost $3,000 to $4,000 each.

In 1983, when the city will begin failing cars, motorists will be required to have car engines tuned at a city-approved garage or service station, which will than issue a reinspection sticker, expected to cost an additional $1, Kozak said.

The program requires that the District fail 15 to 20 percent of the cars inspected in order to force an annual improve in car engine performance. This will be done by making requirements for passing the tests more stringent each year.

Tune-ups for most pre-1981 cars should cost relatively little, Kozak said, and the sophisticated electronic control systems on most 1981 cars are covered by five-year warranties, although they may be expensive to fix when the warranties run out.

"The only really expensive repairs are to catalytic converters, which can cost $250 or more to replace. God, don't use leaded gasoline, it destroys them," Kozak warned.

Last summer when the District randomly tested the exhaust of cars coming into its inspection stations, "we found over 30 percent of the cars could use a tune-up . . . and would have failed."

District officials already fail 30 to 35 percent of the city's cars for safety reasons, Kozak said, so an emissions test failure rate of about 15 to 20 percent won't be that great, he said. "And when the cars are tuned up, they'll not only cause less polution, they'll get better mileage.

EPA reporters say badly tuned engines are a major cause of winter carbon monoxide pollution and the summer ozone smog that have plagued Washington and many urban areas for more than a decade.Both are health hazards. Smog causes coughing and lung damage, and carbon monoxide affects the heart and brain by reducing the capacity of the blood to carry oxygen.

By 1987 the federal emission program "should reduce carbon monoxide by 15 percent and hydrocarbons and ozone by 5 to 10 percent" in the District and 28 states, according to Cackette.

The New Jersey program, on which the District's will be modeled, has contributed to a 40 percent reduction in carbon monoxide pollution in the state since the testing and maintenance program went into effect in 1972, according to EPA officials. While reductions in hydrocarbons in New Jersey, they have been significant in cities -- such as San Francisco -- that also hae instituted testing programs, according to the EPA.

Emissions from motor vehicles have dropped significantly since 1968, when federal air pollution regulations first went into effect -- a 96 percent drop in hydrocarbons and ozone and a 76 percent drop in carbon monoxide, according to a draft report of the National Commission on Air Quality.

But while vehicle emissions will continue to decline as older cars leave the road, the report says malfunctions of sophisticated electronic emission control systems in new cars and use of leaded gas in cars with catalytic converters will lead to emissions well above federal standards. The still-unpublished report of the 13-memmber commission supports a national vehicle inspection and maintenance program.