WRENCHIFY
Quick decodeBack to home
All codes/P0604

P0604

Internal Control Module Random Access Memory (RAM) Error

High severity

ECU self-test detected a RAM fault during runtime checks. This is an internal ECU defect; replacement or reflash with manufacturer support is generally required.

ECU self-test detected a RAM fault during runtime checks. This is an internal ECU defect; replacement or reflash with manufacturer support is generally required.

Common causes

  • ECU internal RAM fault

    One of the most commonly reported causes for this code — check this first.

    high

    Typical part cost: $440-2200

  • Module software outdated, reflash may resolve

    Less common, but worth ruling out after the more likely causes.

    low

    Typical part cost: $440-2200

  • See all causes + fix costs

    Create a free Wrenchify account to unlock the rest for P0604.

    Unlock causes

    Free forever · No credit card

First things to check

  1. 1Confirm the code with a scan tool and check for additional related codes.
  2. 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

Get the full step-by-step diagnosis

Create a free Wrenchify account to unlock the rest for P0604.

Unlock diagnosis

Free forever · No credit card

Tools you may need

Already have a compatible scanner? Use it. If not, a Bluetooth OBD2 adapter can help you confirm engine codes and check supported live sensor data before replacing parts.

Illustration of a Bluetooth OBD2 adapter, not a product photo

Basic checks

Veepeak OBDCheck BLE

A Bluetooth LE adapter for reading standard engine codes and supported live data.

View on Amazon
Illustration of a Bluetooth OBD2 adapter, not a product photo

Regular diagnostics

vgate iCar Pro BLE 4.0

A Bluetooth LE adapter with an automatic sleep feature for routine code and sensor checks.

View on Amazon
Illustration of a Bluetooth OBD2 adapter, not a product photo

Another option

OBDLink CX

A Bluetooth LE adapter to consider when comparing supported vehicles and diagnostic apps.

View on Amazon

Illustrations shown, not product photos. Check vehicle, phone and app compatibility before buying. These adapters do not guarantee access to ABS, airbags or manufacturer-specific systems. Clearing a code does not repair the fault and can reset emissions readiness monitors.

As an Amazon Associate, Wrenchify earns from qualifying purchases. This supports the app at no extra cost to you.

Related codes

See related trouble codes

Create a free Wrenchify account to unlock the rest for P0604.

Unlock related codes

Free forever · No credit card

Frequently asked questions

What does P0604 mean?

P0604 means "Internal Control Module Random Access Memory (RAM) Error". It is a generic OBD-II code that points to a fault in the computer & auxiliary output controls.

What are the most common causes of P0604?

ecu internal ram fault; module software outdated, reflash may resolve; supply voltage outside specification — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.

Get the full P0604 diagnosis for your vehicle

Year, make, model + step-by-step repair help — free plan included.

Diagnose P0604