P0604

Internal Control Module Random Access Memory (RAM) Error

Q: Is it safe to drive with P0604?

Be careful. The module reporting an internal memory error can cause unpredictable running, stalling, or a no-start. Have it diagnosed before depending on the vehicle.

Q: Can I just clear P0604?

It may clear temporarily, but if the battery/grounds are bad or the module is failing it returns. Fix the power supply first, then reassess the ECM.

ECM / control module Generic OBD-II High

What it means

P0604 means the engine control module has detected an internal error in its own RAM (working memory). Because the ECM manages fuel, ignition, and more, this can cause reduced power, stalling, or a no-start. It is often triggered by a weak battery or poor power/ground connections rather than a truly dead module, so those are worth checking before condemning the ECM.

High

Can I keep driving? Drive cautiously — an internal module fault can trigger limp mode, stalling, or even a no-start, so get it diagnosed before relying on the car.

Real-world scan data

Seen in

164

scans in the past year

Found in

<0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0604 scans

P0606in 65.2% of scans

P0602in 58.5% of scans

P0500in 46.3% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Reduced power or limp mode
Stalling or rough running
Hard starting or, in some cases, a no-start

Common causes

Most likely first

Low battery voltage or a weak/failing battery upsetting the moduleLikely
Poor power or ground connections at the ECMCommon
Corrosion or moisture in the ECM connectorsCommon
Internal ECM RAM fault (the module itself failing)Less often
Interrupted or corrupted software after a battery disconnect or bad flashLess often

How to diagnose & fix

Work through it in order

Test the battery and charging system; a weak battery is a common trigger for internal-memory codes.
Inspect and clean the ECM power and ground connections and connectors.
Clear the code and see if it returns after a few drive cycles.
Check for a manufacturer reflash/software update for the ECM.
If the fault persists with good power and grounds, the ECM likely needs reprogramming or replacement.

FAQ

Quick answers

Is it safe to drive with P0604?+

Be careful. The module reporting an internal memory error can cause unpredictable running, stalling, or a no-start. Have it diagnosed before depending on the vehicle.

Can I just clear P0604?+

It may clear temporarily, but if the battery/grounds are bad or the module is failing it returns. Fix the power supply first, then reassess the ECM.

Read & clear P0604 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX