DTC P0601 Or DTC P0603: Condition
WARNING: This page is about a different car, the 2002 Suzuki Esteem. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0601 is set when a data write error or check sum error is written to ECM. DTC P0603 is set when EEPROM memory error occurred. ECM continuously monitors this circuit. MIL is illuminated when ECM detects malfunction during 2 consecutive drive cycles. Possible cause is ECM malfunction.