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Engine computer and electrics

P0604 Control module: internal memory or software fault (RAM)

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P0604 means: Control module: internal memory or software fault (RAM). The fault is in the control module's own memory, processor, supply or internal circuits. Drive gently and have the car checked soon. The repair usually costs about €50–1200 in Estonia. The most common cause: weak battery or unstable voltage.

Is it safe to drive?Get it checked soonDrive gently and have the car checked soon.
Typical repair cost€50–1200parts and labour in Estonia

What it means

The fault is in the control module's own memory, processor, supply or internal circuits. Often the real cause is a weak battery or a bad ground.

What you may notice

  • Engine light on
  • The car may go into limp mode
  • The engine may not start
  • Other modules may also log faults

What could be wrong

  1. 1Weak battery or unstable voltage
  2. 2Bad ground or supply wire
  3. 3Faulty module software
  4. 4Internal module failure (moisture or age)

Repair difficulty: Hard

What you can check yourself

Check the battery and terminals before anything else. If the fault appeared after a battery change or jump start, clear it and see whether it returns. Best left to a workshop. It needs a diagnostic tool and experience.

How we fix it

  1. We measure battery voltage and module supplies
  2. We check the grounds
  3. We update or reflash the software
  4. We repair or replace the module and code it

Standard SAE description: Internal Control Module Random Access Memory (RAM) Error

This code usually comes with: Check engine lightSee what the light means →

Related symptoms: Loss of power or limp mode

Want a definite answer?

Bring the car to our workshop in Estonia for diagnostics. We read the fault codes, test the sensors and tell you what is wrong. Repair price depends on the work involved, generally €45 per hour.

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Questions

What does fault code P0604 mean?

Control module: internal memory or software fault (RAM). The fault is in the control module's own memory, processor, supply or internal circuits. Often the real cause is a weak battery or a bad ground.

Can I drive with code P0604?

Drive gently and have the car checked soon.

How much does it cost to fix P0604?

Roughly €50–1200 in Estonia. The price depends on exactly what has failed and on the car.

How is P0604 fixed?

We measure battery voltage and module supplies. We check the grounds. We update or reflash the software. We repair or replace the module and code it.

Related codes

P0605Control module: internal memory or software fault (ROM)P0603Engine computer lost its learned valuesP0600Control modules can't communicate with each otherP0601Fault in the engine computer memoryP0602Control module: internal memory or software fault (programming)B1600PATS: key transponder signal not received

Based on AI combined with our hands-on workshop experience and knowledge. This information is general and prices are approximate (Estonian workshop rates). The same code can mean different things on different cars. Only an inspection of the car gives a definite answer.

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