What does fault code P0603 mean?

Internal Control Module Keep Alive Memory Error. ECM's keep-alive memory (learned values, stored between key cycles) failed.

P0603

Internal Control Module Keep Alive Memory Error

Q: What are the symptoms of P0603?

Learned idle/shift values reset; Temporary rough running after reset

Q: What are the possible causes of P0603?

Battery disconnected/dead recently; Internal ECM fault; Voltage interruption

Q: How to fix P0603?

Clear codes and allow relearn; If recurring without battery events, ECM may need replacement

Severity: Medium Computer Output Circuit Generic OBD-II Code Est. Repair: $0 - $1,000

Schedule diagnosis soon. Continued driving may worsen the issue.

Quick Answer

P0603 means “Internal Control Module Keep Alive Memory Error.” Severity: Medium. Estimated repair cost: $0 - $1,000. Most common sign: Learned idle/shift values reset.

What Does P0603 Mean?

ECM's keep-alive memory (learned values, stored between key cycles) failed.

Common Symptoms

Learned idle/shift values reset

Temporary rough running after reset

Possible Causes

Battery disconnected/dead recently

Internal ECM fault

Voltage interruption

How to Fix P0603 – Repair Guide

Clear codes and allow relearn

If recurring without battery events, ECM may need replacement

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Budgeting for This Repair?

A typical P0603 repair runs about $0 - $1,000. If you'd rather spread the cost over time, estimate the payment with our free sister tool: Car Finance Calculator (50-state sales tax, trade-in equity, full amortization).

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Disclaimer: Information is for educational reference only and does not replace professional diagnosis. Actual causes and costs vary by vehicle make, model, year and condition. Always verify with a qualified technician.