P0603: Internal Control Module Keep Alive Memory (KAM) Error

What it means

The control module detected an error involving its keep-alive memory (KAM). The code does not by itself mean that a recent battery disconnect or low voltage caused it.

At a glance

• Usually lights the check-engine light

How it works

Keep-alive memory (KAM) stores learned control values while the vehicle is switched off. P0603 sets when the module detects a fault with retaining or checking that memory; low voltage or a battery disconnect can contribute, but the code alone does not prove either caused it.

Common causes

Most likely first.

1. Battery disconnected or voltage too low
2. ECU internal memory fault
3. Module software outdated, reflash may resolve

Symptoms

• Check engine light on
• Possible limp mode or no-start
• Multiple follow-up faults across modules
• Reset/relearn may be needed after repair

How to diagnose it

1. Record freeze-frame data and all module codes, noting whether other faults suggest a recent low-voltage or power interruption.
2. Check battery condition, charging operation, and battery-terminal tightness before investigating the module itself.
3. Inspect the control module's power, ground, and connector condition for corrosion, looseness, or damage.
4. Check whether learned settings were recently reset and follow the manufacturer's procedure for any required relearn.
5. If P0603 returns with stable power and sound connections, check for applicable software updates and evaluate the module's KAM circuitry.

Common fixes

• Clean and secure battery terminals and repair poor module power or ground connections.
• Correct battery or charging-system problems that cause low or unstable voltage.
• Perform the required relearn after a confirmed memory reset.
• Reprogram or replace the module if a persistent internal memory fault is confirmed.

Can I keep driving?

If the vehicle runs normally, limited driving is usually reasonable, but expect learned settings to reset and monitor for rough running or starting trouble. Avoid driving if it stalls, will not restart, or develops other control problems.