Leaders of Fairfax County's government, business community and consumer organizations plan to announce today an precedented "code of business ethics" that has been adopted voluntarily by companies doing business in the Northern Virginia county.

The code, first of its kind developed in the Washington area and apparently the only one in the country designed for a specific market, requires companies tht belong to the Fairfax Chamber of Commerce to post all prices, provide redress for consumer complaints, clean up advertising, train employees to be knowledgeable about products and fight within their industries to correct unethical practices.

Persons who drafted the code said they hope it will be emulated across the country, thus eliminating dollars and government man-hours now devoted to solving "marketplace irritants" and freeing government to act on major issues - including those that may need to be addressed by legislation.

At a news conference scheduled for this morning, the code of ethics will be unveiled. Drawn up by county's Consumer Protection Commission and subsequently modified by the county's Chamber of Commerce, the code details ethical responsibilities not only for business but also for consumers.

Paul S. Forbes, a member of the county consumer commission and a member of the chamber consumer committee, calls the code "a breakthrough in business-consumer relations where it really counts - at the local level where most transactions take place."

In remarks prepared for today's meeting, in the Rayburn House Office Building, Forbed says it has been traditional for chambers of commerce and consumer groups to "regard each other suspiciously as potential or actual adversaries in the marketplace."

The Fairfax County effort, he says, has developed a new program through dialogue and cooperation. He describes the code as anything advocated by consumer groups."

Adherence to the code will be a condition of membership in the county's chamber and members who refuse to abide by its terms will be brought before the group's board of directors for a hearing. If corrective action is not taken the firm will be expelled, according to Forbes, an aide to Giant Food Inc. president Joseph B. Danzansky.

Forbes said the chamber proposed "strenthening, not weakening the code," when presented with a first draft from the consumer protection commission. Among specific requirements in the code for businesses are the following:

Companies must make "very reasonable effort" to become aware of th existence of dangerous products and remove them from sale when discovered.

Businesses must inform consumers in advance of all costs, make certain that advertising is honest and actively work against unethical practices in their industries.

Firms must be willing to protest to manufacturers and professional associations on behalf of consumers if a product or service is defective and must agree to seek a neutral third party settlement of disputes with consumers.

The code requires consumers to familiarize themselves with company policies on redress in the event of disputes and advises consumers not to partonize firms that engage in deceptive or illegal practices. Consumers also must not change price labels on goods and must pay promptly under terms of credit agreements, according to the code.

The announcement today follows the recent release of a nationwide Louis Harris survey, which showed broad public support for the consumer movement and deep disenchantment with the business community's response to consumer needs.

According to the survey, conducted for Sentry Insurance, business leaders are not in touch with the public's surveyed believe that the lives of products will get shorter and that it will be more difficult to get products repaired in the future.