DTC P0604: Internal Control Module Random Access Memory (RAM) Error: Procedure

WARNING: This page is about a different car, the 2009 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DTC
1. Clear DTC. Refer to DTC CHECK / CLEAR .
2. Turn the engine switch Off.
3. Disconnect the battery negative terminal and wait for 1 minutes.
4. Connect the battery negative terminal.
5. Turn the engine switch Off.
6. Check DTC.
  OK
  
  P0604 is not present.
NG → REPLACE ECM

OK → CHECK FOR INTERMITTENT PROBLEMS