How is fault code P0604 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Check the battery before you touch anything else. Resting voltage should be over 12.4V, and it should hold above 9.5V while cranking. A weak battery is the usual culprit and the cheapest to rule out 2. Pull every stored code and note the order they logged in. P0604 alongside other module codes points at a power or earth problem rather than a single dead part 3. Inspect the battery terminals and the main engine earth straps for corrosion, green fur, or a loose clamp 4. Run the engine and measure charging voltage. You want a steady 13.5 to 14.5V. Anything jumping around or below that means the alternator is suspect 5. Clear the code and road test. If it stays away, you were chasing a voltage glitch, often from a jump-start or a battery that went flat 6. If it comes straight back with healthy power and earths, check the ECU connectors and loom for damage or water ingress before condemning the module

Internal Control Module Random Access Memory (RAM) Error

Jump to the fix

Severity

Medium

Can I keep driving?

Usually drivable, but get it diagnosed without delay.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Check the battery before you touch anything else. Resting voltage should be over 12.4V, and it should hold above 9.5V while cranking. A weak battery is the usual culprit and the cheapest to rule out 2. Pull every stored code and note the order they logged in.

PPowertrain
0Generic code
6Computer Output
04Sequence number

What does it mean?

P0604 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Internal Control Module Random Access Memory (RAM) Error . This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.

Symptoms

Likely causes

How to fix it

Codes From the Same System

All Fault Codes

Related Similar Codes

This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.