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ElectricalSeverity High: diagnose before driving on

P0604Internal Control Module Random Access Memory (RAM) Error

What it means

The ECU found an error in its working memory.

Symptoms

  • Check engine light
  • Possibly no start, stalling or limp mode
  • Other codes may be stored at the same time

Common causes

  • Low voltage or poor ground at the ECU
  • Water ingress or corrosion in the ECU or its connector
  • Software problem (update may exist)
  • Internal ECU fault

What to check first

  1. Check ECU power and ground supplies under load
  2. Check the ECU and connectors for water or corrosion
  3. Look for a software update or technical bulletin before replacing the ECU
Can I drive with P0604? Not recommended. P0604 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

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P0604: questions and answers

What does P0604 mean?

P0604: Internal Control Module Random Access Memory (RAM) Error. The ECU found an error in its working memory.

What are the symptoms of P0604?

Check engine light. Possibly no start, stalling or limp mode. Other codes may be stored at the same time.

What causes P0604?

Low voltage or poor ground at the ECU. Water ingress or corrosion in the ECU or its connector. Software problem (update may exist). Internal ECU fault.

How do you diagnose P0604?

1. Check ECU power and ground supplies under load 2. Check the ECU and connectors for water or corrosion 3. Look for a software update or technical bulletin before replacing the ECU

Can I drive with P0604?

Not recommended. P0604 can lead to stalling, limp mode or engine damage; diagnose it before driving further.