Chrysler LLC is uncertain when it can resume production at four assembly plants shut down after a defective part was discovered in the auto maker’s 4.7L V-8.

Affected are Dodge pickup plants are in Warren, MI, and Fenton, MO; a Detroit site that builds the Jeep Grand Cherokee and Commander SUVs; and a Newark, DE, facility that builds Dodge Durango and Chrysler Aspen SUVs. However, Warren, Detroit and Newark already were scheduled for a one-week shutdown starting Sept. 3.

Chrysler has not confirmed which supplier is implicated, nor has it identified the faulty component. But a spokesman tells Ward’s that a fix has been developed and is being implemented.

The auto maker is mum on how much production was lost.