P0603: Internal Control Module Keep Alive Memory Error
The P0603 code indicates that the Engine Control Module (ECM) has detected an internal error in its Keep Alive Memory (KAM). KAM stores adaptive learning data such as fuel trims and idle settings, which are retained when the ignition is off. This error typically occurs due to low battery voltage, a faulty ECM, or wiring issues. It can cause drivability problems and may trigger the Check Engine Light.
1. Most Common Causes
- Low battery voltage or dead battery
- Faulty ECM or internal memory failure
- Corroded or loose battery terminals
- Blown ECM fuse or wiring issues
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Poor fuel economy or hesitation
- Loss of adaptive memory (e.g., radio presets)
3. Step-by-Step Diagnosis
Step 1: Check battery voltage and terminals; clean and tighten if needed.
Step 2: Inspect ECM fuses and wiring for damage or corrosion.
Step 3: Clear the code and test drive; if it returns, check for other codes.
Step 4: If persistent, test ECM power and ground circuits; replace ECM if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It may be safe for short trips, but the vehicle could stall or run poorly. It's best to diagnose and fix promptly to avoid further issues.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and simple fixes like battery cleaning; ECM replacement can cost $500-$1000.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.