The Environmental Protection Agency is set to order the recall of every 1976 auto manufactured by American Motors Corp., according to sources in the agency.

The recall of an estimated 310,000 cars, expected to be announced at a press conference today, is due to problems with the automobiles' emission control systems.

It is the first time a federal agency has recalled every car manufactured by an auto company in an entire production year.

In an apparent attempt to head off effects of the government action, American Motors announced its own recall of the same cars late yesterday, but an EPA official called the announcement "too little, too late."

According to American Motors, the recall will check a back pressure sensor in the exhaust gas circulation valve system, which may be broken and will be replaced by dealers at no cost. The condition has no noticeable effect on engine performance or safety, AMC said.

AMC spokesman Richard Priebe said the problem involved emission control failure after a car "had been on the road and in use a while."

Essentially, he said, some of the cars might not be meeting EPA requirements for control of oxides of nitrogen (NOX).

Most of the cars have six-cylinder engines displacing 258 or 232 cubic inches, Priebe said.

The 1976 production list ranges from traditional passenger vehicles (270,000 to Jeeps (40,000) and some "general dispatch" vehicles - the small special order minitrucks used by the U.S. Postal Service.

The passenger cars involved are Gremlins, Pacers, Hornets and Matadors.

"We have been working with the EPA for some time on this problem," Priebe said, but he said he did not know if the company's recall was designed to lessen the impact of the EPA action.

"What they did will become moot tomorrow morning," an EPA spokesman said yesterday of the AMC action. "There is a world of difference between a car company ordering a recall and the EPA ordering one."

He explained that under an EPA recall, the company's corrective action must be approved by the agency. That is not the case when the company orders the recall.

In addition, under an EPA recall, a firm must send letters to all owners warning of the problem and announcing the recall. A company-originated recall frequently involves only an announcement to the press.

Priebe said he had no figures on how much the recall would cost AMC, which is severely strapped financially.

AMC recently announced an agreement to market Renault cars in the United States, and only yesterday Renault said it expected to extend "tens of millions of dollars" in credit to its new partner in order to help AMC begin assembling Renaults in its Kenosha, Wis plant.

Financially, AMC has been in bad shape for several years. Its recently announced quarterly earnings reported in increase in sales from $534 million to $640 million, but a corresponding increase in profits of only $200,000 to $2.7 million.

The EPA action could have a serious effect on the company, which has had cash problems.