DTC P0601: ECM Memory (Checksum Error)
- Check the ''On Board Diagnostic (OBD) System Check''.
Was the ''OBD System Check'' performed?
YES – Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM. 
NO – Go to OBD System Check.
DTC P0606: Redundant Overrun Monitoring (ECM Internal Error)
- Check the ''On Board Diagnostic (OBD) System Check''.
Was the ''OBD System Check'' performed?
YES – Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original ECM.
NO – Go to OBD System Check.