P0603

Internal Control Module Keep Alive Memory (KAM) Error

Engine control module (ECM) Generic OBD-II High

What it means

P0603 means the engine control module found a fault in its keep-alive memory — the small amount of storage kept powered with the key off so the ECM remembers learned fuel trims and idle settings. It's often triggered by a weak battery, a bad ground, or losing constant power, and until those learned values are restored the engine can idle rough, start hard, or stall.

High

Can I keep driving? Be cautious — the ECM has lost its learned settings, which can cause rough running, hard starting, or a no-start, so get it diagnosed promptly.

Real-world scan data

Seen in

291

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

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
Rough or unstable idle and poor drivability after startup
Hard starting or intermittent no-start
Other monitors won't complete / readiness not set

Common causes

Most likely first

Weak, dead, or recently disconnected battery (KAM loses its keep-alive power)Likely
Corroded or loose battery terminals or ground connectionsCommon
Charging-system problem or voltage drop on the KAM power feedCommon
Wiring fault in the constant-power (memory) circuit to the moduleLess often
Internal ECM faultLess often

How to diagnose & fix

Work through it in order

Load-test the battery and inspect/clean the battery terminals and main grounds first.
Check the charging-system voltage and the ECM's constant-power (KAM) fuse and feed.
Verify the memory circuit holds voltage with the key off.
Clear the code, let the ECM relearn idle/fuel trims over a few drive cycles, and re-check.
If the code returns with good power and grounds, the ECM likely needs reprogramming or replacement.

FAQ

Quick answers

Is it safe to drive with P0603?+

Drive cautiously. The ECM has lost its learned adjustments, so idle and starting may be rough and it can stall until power/ground faults are fixed and it relearns.

Can I just clear P0603?+

You can, and it may clear if triggered by a one-time battery disconnect — but if the battery, grounds, or memory circuit are faulty it will return.

Read & clear P0603 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