DETROIT (AP) — The Federal Trade Commission is investigating General Motors because of dealers who advertised certified used cars for sale even though they still needed repairs under existing recalls.

The agency notified GM of the probe on June 3, and it was disclosed by the company Thursday in a quarterly report to securities regulators.

GM said in the filing that it’s investigating and cooperating with the probe. A spokesman wouldn’t give further details.

Federal law bans the sale of new cars with unfixed recalls, but dealers can legally sell used cars that haven’t been fixed.

It’s unclear what the agency is looking into or what law may have been broken. An FTC spokesman wouldn’t comment.

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