By a single vote, the House last night beat back a major challenge to the most important civil rights bill in a dozen years.

On a 205-to-204 vote, the House endorsed the bill's key provision in a substantial victory for the president, House civil rights forces and the Leadership Conference on Civil Rights.

The vote sustained the heart of the 1980 housing civil rights bill, which gives the Housing and Urban Development Department strong administrative enforcement powers, for the first time, to carry out the 1968 housng anit-discrimination law.

The bill would provide what advocates called "real enforcement teeth" for HUD, using administrative law judges chosen by the Justice Department to take jurisdiction over housing discrimination complaints and issue enforcement orders including fines of up to $10,000.

William L. Taylor, Frank Polhaus and other representatives of the more than 100 organization making up the Leadership Conference on Civil Rights said the new procedurre would speed enforcement immensely and relieve the injured parties of the burden of having to go to court themselves.

Under existing law, as laid out in the 1968 Civil Rights Act, a person who believes he or she has been a victim of racial, religious or other discrimination in the sale or rental of housing must go to court personally and bring a costly, time-consuming civil suit. There is no mechanism for any administrative agency to enforce the law.

The dispute last night came over an amendment sponsored by F. James Sensenbrenner (R-Wis.) and Harold L. Volkmer (D-Mo.). Their amendment would have killed the administrative law judge procedure and returned basic enforcement to federal court judges and magistrates. Civil rights leaders said the administrative law judge procedure is faster and less cumbersome and charged that the Sensenbrenner-Volkmer amendment would gut the bill.

But Sensenbrenner indignantly said on the floor, "There is no intent on the part of the gentleman from Wisconsin to gut the bill."

The key vote came when Mike Synar (D-Okla.) offered an amendment that, in effect, wiped out the language of the Sensenbrenner-Volkmer proposal and, with some modifications, restored the procedure favored by the civil rights groups. Synar won, on the 205-to-204 tally.

Earlier yesterday, civil rights groups won another victory on the bill when they defeated, 257 to 156, an effort to permit real estate appraisers to include in their reports language on the racial character of a neighborhood and the presence of churches and synagogues. Opponents, such as the bill's floor manager, Don Edwards (D-Calif.), and John F. Seiberling (D-Ohio), said this kind of information in an appraisal report constitutes "code words" for discrimination that frighten off buyers, mortgage lenders and insurance firms, thereby cutting property values, blocking blacks from home-buying opportunities and eroding black neighborhoods.

The Society of Real Estate Appraisers backed the defeated amendment, which was sponsored by Henry J. Hyde (R-Ill.).

In addition to the administrative enforcement procedure, which bill supporters said is by far the most important provision, the bill contains language barring mortgage "redlining" and banning discrimination in the sale of housing insurance and in appraisals.

Leadership Conference spokesman, clustered in the House corridor during the key vote, said that the bill is the first major initiative in civil rights since the 1968 housing law itself, which barred discrimination in the sale and rental of housing but left enforcement entirely up to the courts.

In the Senate, a similar measure being considered by a Judiciary subcommittee is expected to move shortly to the full committee. Debate in the House, and perhaps final House passage, is expected today.

On yesterday's key House vote, 180 Democrats and 25 Republicans voted with the president and the civil rights leadership group. Opposed were 76 Democrats and 128 Republicans.

In the Maryland delegation, all Democrats except Beverly Byron voted with the president. Byron and both Maryland Republicans voted against. In the Virginia delegation Joseph L. Fisher (D), Herb Harris (D) and Caldwell Butler (R) voted with the president while the others voted against.