A small Tesla Inc. contractor has sued the auto maker claiming it hasn’t been paid for work at a Fremont, Calif., assembly plant where Tesla is now trying to ramp up production of the Model 3 sedan.

American Integrated Services Inc. claims Tesla hasn’t paid $513,473 for lead and asbestos abatement-related work under a $3.57 million contract signed in January 2016. It filed the lawsuit Tuesday in a California state court in Oakland.

Tesla called the matter “a minor commercial dispute.”

“We paid AIS for all the work we authorized them to do,” a Tesla spokesman said in a statement Friday. “The additional payment they’re seeking is for work that we did not authorize and that clearly was unnecessary. When we asked for documentation showing that Tesla had authorized this unnecessary work, they were unable to provide it.”

The claim comes as the auto maker faces questions about its cash level while it spends heavily to ramp up production of the Model 3, a compact sedan that is designed to turn the electric-car maker from a niche player to one that sells to the masses.