P0603: How to Diagnose & Fix — Internal Control Module Keep Alive Memory (KAM) Error
2 vehicles · 2 makes · $150-$900 repair
How to diagnose and fix P0603: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford Explorer · 2025–2025
On certain 2025 Explorers built December 6, 2023 through September 6, 2024 with the 2.3L EcoBoost, the powertrain control module (PCM) can unexpectedly reset while the vehicle is operating. The reset can damage the transmission's park system or cause the engine to stall. A damaged park system can let the vehicle roll away when shifted to Park without the parking brake applied, and an engine stall produces a sudden loss of drive power. Approximately 24,655 vehicles are covered. Ford traced the resets to an error in the PCM software and reported no crashes or injuries when it filed the recall.
Common Symptoms
- Vehicle rolls away after being shifted to Park
- Sudden loss of drive power / engine stall while driving
- Warning lights or messages on the dashboard
- Transmission not holding in Park
How to Fix
Visit a Ford dealer for the free recall remedy under campaign 25S35 (NHTSA 25V239000): dealers reprogram/update the powertrain control module software and inspect the transmission park system, replacing it if damaged. Until repaired, always set the parking brake when parking. Owner notification letters were mailed June 6, 2025. Ford customer service: 1-866-436-7332.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (3)
Nissan Frontier · 2022–2024
Owners of the new-generation Frontier have reported intermittent no-start events, extended crank, or occasional stalling tied to control-module logic, battery state sensitivity, or software calibration issues. Complaints commonly describe the truck acting like a weak battery or failing to restart normally despite the battery testing good. Nissan has issued service information and software-related fixes for some starting and drivability complaints on this platform.
Common Symptoms
- Intermittent no-start
- Extended cranking
- Truck starts after multiple attempts
- Random stall or restart issue
- Battery tests good but symptoms persist
How to Fix
Begin with battery load testing, charging-system verification, and a scan for stored or pending codes in the ECM, BCM, and IPDM. If hardware checks out, dealers typically look for applicable ECM/TCM/BCM software updates and reprogram as needed. Poor battery condition or loose grounds should be corrected before module updates are performed.
Owner tips & cautions
- TipHave the battery tested with a real load tester, not just voltage checked; many owners found weak OE batteries caused confusing electronic symptoms.
Sources for this issue (1)
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P0603 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0603 mean?
P0603 stands for "Internal Control Module Keep Alive Memory (KAM) Error." This code means the engine computer's keep-alive memory (KAM), which stores learned adaptive values and settings between key cycles, has failed an internal check. The PCM relies on this memory to retain fuel trims, idle learning, and other adaptations. A KAM error can cause rough running, poor fuel economy, or transmission shift issues until the module relearns or is repaired.
What are the most common causes of P0603?
The most common causes of P0603 are: Loss of constant battery power to the PCM (blown fuse, bad connection), Weak or failing battery, Corroded or loose battery/ground connections, Recent battery disconnection without relearn, Internal PCM fault, Damaged PCM power/ground wiring. The specific cause varies by vehicle.
How much does it cost to fix P0603?
Repair costs for P0603 range from $150 to $900, depending on the vehicle and root cause.
Which vehicles are affected by P0603?
Au7o has documented P0603 across 2 vehicle models from 2 manufacturers: Ford, Nissan.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.