Monitor Description
WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
The engine stop and start ECU continuously monitors its internal memory status. This self-check ensures that the engine stop and start ECU is functioning properly. The engine stop and start ECU memory status is diagnosed by internal mirroring of the main CPU and sub CPU to detect Random Access Memory (RAM) errors. If outputs from these CPUs are different and deviate from the standard, the engine stop and start ECU will illuminate the MIL and store this DTC.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Warning Indicate | DTC Output from | Priority | Note |
|---|---|---|---|---|---|---|---|---|
| P0604-44 | Internal Control Module Random Access Memory (RAM) Error Data Memory Failure | Engine stop and start ECU RAM error (1 trip detection logic). | Engine stop and start ECU | Comes on | Does not come on | Stop and Start | A | SAE Code: P0604 |