What is the test for a defendant to appeal against a concurrent sentence under section 654 of the California Criminal Code?

Although defendant did not object to concurrent sentencing on these counts, the issue is not forfeited. "This is an exception to the general rule that only those claims properly raised and preserved by the parties are reviewable on appeal. This exception is not required by the language of section 654, but rather by case law holding that a court acts in excess of its jurisdiction and imposes an unauthorized sentence when it fails to stay execution of a sentence under section 654." (People v. Hester (2000) 22 Cal.4th 290, 295.)