P0604 Code: Internal Control Module Random Access Memory (RAM) Error
🟠 Moderate severity · drivable
Drivable, but the PCM's memory is failing, which usually means the module needs to be replaced.
What P0604 means
The engine control module has detected a fault in its internal random access memory (RAM). This is usually a sign the PCM itself is failing.
Symptoms
- Check engine light is on
- Intermittent running problems
- Multiple unrelated codes
- Possible stalling
Common causes
- most common: Faulty engine control module (PCM)
- common: Low battery voltage
- less common: Failed software update
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Test the battery and charging system | Yes | $100–250 |
| Reprogram or replace the engine control module | Mechanic | $300–1500 |
Frequently asked questions
Can I drive with a P0604 code?
Sometimes, but the PCM is failing. Plan to replace or reprogram it soon.
What is the most common cause of P0604?
A faulty engine control module.
How much does it cost to fix a P0604?
Reprogramming is $100–$300; a replacement PCM is $500–$1,500.
Related codes
P0601
P0601 Code: Internal Control Module Memory Check Sum Error
P0605P0605 Code: Internal Control Module Read Only Memory (ROM) Error
P0606P0606 Code: ECM/PCM Processor Fault
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.