Tesla Inc.’s engineering chief won’t return from his leave of absence, a person familiar with the situation said, as the auto maker heads into a pivotal period to prove it can sustain production of the Model 3 sedan.

Doug Field, who had been senior vice president of engineering, stepped away from his work overseeing product development at the Silicon Valley auto maker in early May. At the time, a Tesla spokesman said, “Doug is just taking some time off to recharge and spend time with his family. He has not left Tesla.”

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