DTC P0604 Internal Control Module Random Access Memory (RAM) Error: Description
WARNING: This page is about a different car, the 2007 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
The ECM continuously monitors its internal memory status. This self-check ensures that the ECM is functioning properly. It is diagnosed by internal "mirroring" of the main CPU and sub CPU to detect the Random Access Memory (RAM) errors. If outputs from these CPUs are different and deviate from the standards, the ECM will illuminate the MIL and set a DTC immediately.
DTC DETECTION CONDITION
| DTC | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0604 | ECM RAM errors (1-trip detection logic) | ECM |