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Home / Codes / P0603
DTC code page

P0603: Internal Control Module Keep Alive Memory Error

Quick answer: The PCM lost or failed its keep-alive memory, usually because memory power or the module itself became unstable.

Drivers also search this fault as keep alive memory error, PCM memory reset code, P0603 KAM error.

Severity: medium Family: powertrain Related paths: 11
Meaning

What P0603 usually means

P0603 sounds like a dead computer every time, but in the field it often starts as a power-history problem. Keep-alive memory is the part of the PCM that stores learned values and some retained information when the key is off. If battery voltage drops too low, the PCM loses its memory feed, the fuse path opens, or the module itself becomes unstable, P0603 can set. That makes battery condition, fuses, relay feeds, and recent jump-start or module work just as important as the PCM itself.

Fast triage

Start here before chasing parts

  • Scan first: save freeze-frame and pending codes before clearing anything.
  • Confirm the complaint: compare the stored code with current drivability symptoms.
  • Use context: trims, live data, and related codes usually narrow the fault faster than guesswork.
  • Work simplest to hardest: leaks, connectors, maintenance items, and known patterns before expensive components.
Initial checks

What to check first

  • Check battery voltage, charging health, and whether the battery was recently disconnected or went dead.
  • Inspect the PCM memory fuse and related power-feed path before condemning the module.
  • Ask whether drivability changed only after a jump-start, module swap, or electrical work.
Driving risk

Can you keep driving?

P0603 is not always an immediate stop-driving code, but it should not be treated like harmless trivia if starts, communication, or voltage behavior are unstable.

Moderate urgency: This code often allows short-term driving, but the right fix usually comes faster when you diagnose it early instead of waiting for more codes.
Likely causes

Common causes behind this code

  • Weak battery or repeated low-voltage events resetting keep-alive memory
  • Blown or intermittent PCM memory fuse or feed circuit issue
  • Poor ground or unstable main power supply to the PCM
  • Recent battery replacement, jump-start, or module work
  • Internal PCM memory failure if external power paths are proven good

Cause phrases often tied to this code: weak battery, PCM memory fuse, power relay issue, bad ground, PCM fault, recent jump start.

Diagnostic order

Suggested workflow

  1. Test battery state and charging-system output so low voltage is either confirmed or ruled out first.
  2. Verify the PCM keep-alive feed, ignition feed, and grounds stay stable with key off and key on.
  3. Inspect relevant fuses, relay paths, and connector fit at the PCM and power-distribution center.
  4. Review companion low-voltage, relay, communication, or ignition-switch codes that may explain why memory was lost.
  5. Only move toward PCM replacement or reprogramming after the external power story is solid.
Avoid guesswork

Common mistakes

  • Replacing the PCM when a battery, fuse, or ground problem keeps resetting it.
  • Ignoring jump-start history or repeated low-voltage episodes.
  • Clearing P0603 without checking whether other power-supply codes are telling the real story.
Repair path

Practical fix guidance

  • Fix the voltage, fuse, relay, ground, or module problem that caused keep-alive memory loss.
  • If the PCM was replaced or reflashed, verify programming and retained power feeds correctly afterward.
  • Confirm learned values can rebuild normally and the code does not return over several key cycles.
Vehicle context

Affected brands in this MVP

Brand hubs help broaden internal linking now and can evolve into make-specific diagnostic notes later.

Aliases and common searches

English phrases tied to P0603

Useful when the driver knows the wording but not the exact DTC yet.

  • keep alive memory error
  • PCM memory reset code
  • P0603 KAM error
Related search intent

Queries this page can answer naturally

  • P0603 code meaning
  • what does P0603 mean
  • keep alive memory error symptoms
  • P0603 after battery change
FAQ

Quick questions about P0603

Can a weak battery cause P0603?

Yes. Low voltage and repeated battery disconnect events are common real-world triggers.

Does P0603 mean the PCM is bad?

Not automatically. Power-feed and keep-alive memory circuits need to be proven first.

Why did P0603 appear after a battery change?

The PCM may have simply recorded that its keep-alive memory was interrupted during the electrical event.