San Francisco — Five months ago, Pacific Gas & Electric (PG&E) CEO Bill Johnson walked into a room full of California law makers and told them he was the man who would fix the state’s largest utility.

Johnson was 15 days on the job, and PG&E had just been found to have caused California’s Camp Fire, which killed 86 people, leveled an entire town, and landed the company in the biggest utility bankruptcy in US history. “Let’s not do it again,” he said...