Diagnostic & Technical Explanation
Code P0606 (Control Module Processor) sets when a control module's (ECM, PCM, or TCM) internal self-test finds its memory (RAM/ROM/EEPROM/NVRAM/checksum), processor, or an internal signal-processing channel is not functioning correctly. Unlike a sensor circuit fault, this points at the module's own hardware, so the fix path is reflashing the module's software first and, if the fault returns, replacing the module rather than chasing external wiring.