P0604: Internal Control Module Random Access Memory (RAM) Error
Short answer: P0604 means “Internal Control Module Random Access Memory (RAM) Error”. It is a standard OBD-II code, so the basic meaning is the same on every car. Below is what it means on each of the 6 cars we cover, with a link to the full page for each car.
Standard OBD-II code Same meaning on all cars (SAE J2012).
P0604 on each car
| Car | Meaning on this car | Confidence |
|---|---|---|
| Toyota Passo (1st gen) | Internal Control Module RAM Error | low |
| Toyota Corolla (11th gen, E170) | Internal Control Module Random Access Memory (RAM) Error | medium |
| Toyota Corolla (10th gen, E140) | Internal Control Module Random Access Memory (RAM) Error | medium |
| Honda City (5th gen, GM2) | Internal Control Module Random Access Memory (RAM) Error | medium |
| Honda Civic (10th gen, FC) | Internal Control Module Random Access Memory (RAM) Error | medium |
| Suzuki Wagon R (Pakistan, K10B) | Internal Control Module Random Access Memory (RAM) Error | medium |
Symptoms
- Check engine light on
Likely causes
- Possible causes for this code include
- PCM programming error
- New or incorrect PCM
- Aftermarket (high-performance) PCM program installed
- Blown ECM/PCM fuse
- Low battery voltage or complete battery discharge
- Bad ECM/PCM power supply relay
What to check, in order
- Check all battery and ECM power and earth connections first
- Read every stored code; an ECM fault is rare, wiring faults are common
- Have a specialist confirm before replacing the ECM
Causes and checks above are the general meaning. The exact test steps and values differ by car: open your car’s page.