Hi @yongs
The configuration of the CORE_CLK to a frequency of 240 MHz corresponds to Option A+ (High-Performance mode) of the system clocking configuration. To be able to enable Option B/A+(S32K358)/ A++(S32K388) is stated that the "host application must program the UTEST Miscellaneous register (UTEST_MISC): dcf_client_utest and must configure the HSE_CLK_MODE_AND_GSKT_CTRL (bit 30-29) in this register."
For more details, refer to the DCF Clients file in the Device Reference Manual and the HSE_B Firmware Reference Manual.
B.R
VaneB