The House Rules Committee voted yesterday to allow the House to reconsider, and possibly overthrow, a key provision of its new ethics code, which limits the outside income a member can earn to $8,625 a year.

While the rules Committee action does not ensure that the House would throw out the income limit provision, which it adopted with great fanfare as part of the ethics code last year, it does indicate substantial irritation among the members with the ethical strictures they voted upon themselves in the walk of Watergate and the Korean influence-buying scandal.

Part of that code is just beginning to hit home, as members must file by April 30 a detailed financial disclosure statement of their income assets and holdings for the last four months of 1977.

The earned-income limit was not to take effect until Jan. 1, 1979, but it may be responsible for some of the near-record retirements this year.

The bill the Rules Committee cleared for the floor did not deal with the income limit. Instead, it merely attempted to set civil and criminal penalties for violating parts of the code and extended financial disclosure requirements to candidates for Congress and high-ranking members of the executive and judicial branches and the military.

But by a 9-to-7 vote, the committee adopted an amendment by Rep. James H. Quillen (R-Tenn.) that would allow the House to reconsider the income limit.

Rep. Richard Bolling (D-Mo.) said the amendment was "not crippling" but a "problem." But Quillen said the adoption showed "considerable interest" in the House in throwing out the limit.

David Cohen, president of Common Cause, deplored the action. "If you repeal the income limit it's a clear betrayal of the pledge House members took when they voted themselves an increase last year," he said. Last year members increased their salaries from $44,600 to $57,500 a year.

During two days of protracted hearings on the bill Rules Committee members made clear they did not like living under the new ethics rules. The ethics code was a first priority of Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), but, despite the fact that the Rules Committee is supposed to be subject to the speaker and an arm of the leadership, five of the 10 Democrats on the committee voted to reconsider the limit.

Rep. Shirley Chisholm (D-N.Y.), who had substantial income from honoraria which would be limited under the rules, called the financial disclosure requirements a "massive invasion of privacy."

"The fact that many younger members are not running," Chisholm said, indicated that the ethics code and income limit was causing the House to "lose some of its best minds."

Rep. B. F. Sisk (D-Calif.), who is retiring, questioned the constitutionality of the income limit and said the code was so stringent "the best people will want no part of government."

Rules Committee Chairman Mames J. Delaney (D-N.Y.), who discussed during the meeting the substantial trading in stocks he engages in, said the code was "going to make every member of Congress resign," Rep. Morgan F. Murphy (D-Ill.), who would have to curtail his law practice under the limit, said U.S. attorneys would try to make a "political career" by prosecuting members of Congress.

And Quillen suggested that giving the Justice Department the right to prosecute violators of parts of the code could lead to the kind of government control over legislators that exists in communist countries.