P0605

Internal Control Module Read Only Memory (ROM) Error

Engine control module (ECM) Generic OBD-II High

What it means

P0605 means the engine control module has failed an internal self-test of its read-only memory (ROM) — the ECM's own program storage is reporting an error. Because the ECM runs the engine, this can cause stalling, a no-start, warning lights and erratic running. It usually points to the module itself, but check its power and grounds first.

High

Can I keep driving? Treat as serious — an internal ECM fault can cause stalling or a no-start without warning; get it diagnosed before relying on the car.

Real-world scan data

Seen in

441

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0605 scans

P0500in 51.7% of scans

P0303in 50.8% of scans

P0420in 49.4% 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, often with other warning lights
Stalling or a no-start
Poor running or reduced power
Erratic operation or gear-shift problems

Common causes

Most likely first

Poor ECM power supply, ground or reference voltageLikely
Corroded or loose ECM connectorsCommon
Damaged wiring in the ECM circuitsCommon
Corrupted ECM software needing a reflashLess often
Internally failed ECMLess often

How to diagnose & fix

Work through it in order

Check the battery, ECM power feeds and ground connections — a weak supply is the cheapest and most common trigger.
Inspect the ECM connectors and harness for corrosion, looseness or damage.
Clear the code and see whether it returns after a solid supply is confirmed.
Reflash or update the ECM software to the latest calibration per the manufacturer.
Replace or professionally reprogram the ECM only if the internal ROM fault persists.

FAQ

Quick answers

Is it safe to drive with P0605?+

Not really. An internal ECM error can cause stalling or a sudden no-start, so avoid relying on the vehicle until it's diagnosed. Check power and grounds first — it isn't always a dead computer.

Can I just clear P0605?+

You can try, and if a poor power/ground connection set it the code may stay away once that's fixed. If it returns, the ECM needs a reflash or replacement.

Read & clear P0605 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