Congress’ independent ethics review board believes there is “substantial reason” to think a Texas congressman violated conflict-of-interest rules by pushing legal changes that could have benefited his auto dealership.

The House Ethics Committee released on Thursday a report from the Office of Congressional Ethics detailing findings from an investigation into Rep. Roger Williams (R-Texas). The investigation was prompted after Williams proposed a measure last year to exempt auto dealers from a rule prohibiting companies from renting or loaning cars subject to safety recalls if rentals aren’t their primary source of business.

Williams’ auto dealership, the panel found, appear to fit that description, leading to the conclusion that his “personal financial interest in his auto dealership may be perceived as having influenced his performance of official duties.”

The House Ethics Committee said they would continue reviewing the matter.

Williams has not tried to hide his personal connection to the auto industry. In fact, he noted on the House floor as he was promoting his amendment that: “I am a second-generation auto dealer. I have been in the industry most of my life. I know it well.”

But Williams has rejected the suggestion that his actions were unethical, arguing in an official response that he proposed the amendment “without any improper motivations, and without any desire or possible effect of personal gain.”

His office declined to comment further Thursday evening.

The House rules state that members cannot use their influence for personal gain, financial or otherwise.

Williams argued his personal auto dealership business “makes no profit” from facilitating rentals or offering loaner cars, Williams said in the official response, but not exempting auto dealers from the rule could affect up to 16,000 dealerships nationwide.

The Office of Congressional Ethics pointed out in their report that Williams had not cooperated with the review, making it impossible “to determine the extent of the rental services component of the dealership’s business operations … or the revenue generated by the rental business.”

The House adopted Williams’ amendment by voice vote, but it was stripped from the final version of the bill during negotiations with the Senate.