Internal Control Module Keep Alive Memory (KAM) Error
This code indicates that the Powertrain Control Module (PCM) has lost its Keep Alive Memory (KAM), which stores adaptive learning values like fuel trims and idle settings. The engine computer sets this code when it detects an interruption in the constant battery power supplied to the KAM circuit or an internal memory failure.
While the vehicle is usually safe to drive, it may experience rough idling, stalling, or poor shifting until the computer relearns its adaptive values. It should be diagnosed soon to prevent drivability issues and ensure emissions compliance.
Common symptoms
- Illuminated Check Engine Light
- Rough or erratic engine idle
- Engine stalling when coming to a stop
- Harsh or delayed transmission shifting
- Decreased fuel economy
Likely causes
- Recently disconnected, discharged, or replaced battery
- Loose or corroded battery terminals
- Blown KAM circuit fuse
- Damaged wiring or poor connections in the KAM power supply circuit
- Internal Powertrain Control Module (PCM) failure
What to check before replacing parts
Inspect the battery and its terminals.
Look for: Look for loose connections, heavy corrosion, or a weak battery that drops voltage significantly during cranking, which can interrupt KAM power.
Check the KAM or PCM constant power fuse.
Look for: Locate the specific fuse for the PCM keep-alive memory in the fuse box and check if it is blown or has poor contact.
Inspect the wiring harness and connectors leading to the PCM.
Look for: Look for chafed wires, water intrusion, or bent pins that could cause an intermittent loss of constant power to the module.
Measure voltage at the KAM power pin on the PCM connector.
Look for: Use a multimeter to verify that battery voltage (approximately 12.6V) is present at the KAM pin at all times, even when the ignition is off.
Check for PCM software updates or internal faults.
Look for: If power and ground circuits are perfect, check for Technical Service Bulletins (TSBs) requiring a reflash, or verify if the PCM itself has failed internally and requires replacement.
This page explains the generic P0603 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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