P0604: Internal Control Module Random Access Memory (RAM) Error
Can you still drive? Not recommended. A RAM failure can cause unpredictable engine behavior. Have the vehicle towed to a repair facility if possible.
What Does P0604 Mean?
Code P0604 indicates that the PCM has detected a failure in its internal RAM during a self-diagnostic test. RAM is used for real-time data processing including sensor inputs, calculations, and output commands. A RAM failure means the PCM cannot reliably process engine management data.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Internal PCM hardware failure
- Voltage spike or electrical surge damaging PCM circuitry
- Water or moisture intrusion into PCM housing
- Extreme temperature damage to PCM
- Manufacturing defect in PCM
Symptoms
- Check engine light on
- Engine in limp mode
- Poor engine performance
- Multiple random fault codes
- Possible no-start condition
Diagnostic Steps
- 1Clear the code and check if it returns immediately on key cycle
- 2Check for voltage spikes or charging system issues
- 3Inspect PCM and its connectors for water damage or corrosion
- 4Verify PCM power and ground circuits
- 5Attempt a PCM reflash
- 6If code persists, the PCM will need to be replaced
Recommended Parts & Tools
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $300 - $1500 |
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Chat with AI About P0604Commonly Affected Vehicles
Related Recalls
1 Active Recall — 2026 Jeep Wrangler
The following NHTSA safety recalls have been issued for this vehicle. Contact your dealer to check if your vehicle is affected.
CHILD SEAT:VEHICLE TETHER ANCHOR
Chrysler (FCA US, LLC) is recalling certain 2026 Jeep Wrangler vehicles. The child seat tether welds on the second-row, right-side seat frame may be insufficient, which can reduce the seat's ability to properly restrain a child during a crash. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 225, "Child Restraint Anchorage Systems."
Remedy: Dealers will replace the second-row, right-side seat frame, free of charge. Owner notification letters are expected to be mailed May 29, 2026. Owners may contact FCA customer service at 1-800-853-1403. FCA's number for this recall is 27D. Vehicle Identification Numbers (VINs) involved in this recall will become searchable on NHTSA.gov beginning April 16, 2026.
Data provided by the National Highway Traffic Safety Administration (NHTSA).
Frequently Asked Questions
Can P0604 be fixed without replacing the PCM?
Sometimes clearing the code and reflashing the PCM can resolve a soft error. However, if the code returns, the PCM has a hardware failure and must be replaced.
What causes PCM failure?
Common causes include voltage spikes from jump starting, water intrusion, extreme heat, and age-related component degradation.
Community Fix Reports
Community reports are user-submitted and not verified by Auto AI Buddy. Results may vary.
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