P0604
PowertrainPcm Internalhigh severityInternal Control Module Random Access Memory (RAM) Error
What P0604 Means
The PCM detected an internal RAM read/write fault during self-testing. This typically points to an internal processor or memory failure within the module.
Symptoms
- Check engine light on
- Poor engine performance
- Intermittent stalling or no-start
Common Causes
- Faulty PCM internal RAM
- Internal module hardware failure
- Voltage supply instability
- Corrupt module software
Diagnostic Steps
- Verify battery and charging system voltage
- Check PCM power and ground circuits
- Clear code and monitor for recurrence
- Reflash or replace PCM if fault remains
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Community Confirmed Fixes
No confirmed fixes yet for this code. Be the first to contribute!
Submit a FixFound a Fix for P0604?
Help other technicians by sharing what worked on your vehicle.
Submit Your Fix