P0603 on Nissan: How to Diagnose & Fix
Internal Control Module Keep Alive Memory (KAM) Error
1 Nissan model · 1 documented issue · $150-$900 repair
P0603 on Nissan by model: symptoms, diagnosis and fix
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)
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 on a Nissan?
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. On Nissan it is documented across 1 model: Frontier.
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 on a Nissan?
Published repair estimates on Nissan range from $150 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0603 on a different make?
View P0603 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.