P0603: Internal Control Module Keep Alive Memory (KAM) 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, idle speed, and transmission shift patterns. This error typically occurs when the ECM loses power (e.g., battery disconnect, dead battery) or when the KAM circuit fails. It can also be triggered by a faulty ECM, wiring issues, or a blown fuse. The code may cause drivability issues like rough idle, poor performance, or transmission shifting problems.
01. Most Common Causes
- Battery or power loss (disconnected, dead, or low voltage)
- Faulty ECM (internal failure)
- Blown KAM fuse or wiring issues
- Corroded or loose battery terminals
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Rough idle or stalling
- Poor acceleration or hesitation
- Transmission shifting issues (if applicable)
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data. Clear codes and test drive to see if P0603 returns.
Step 2: Check battery voltage and connections. Ensure battery is fully charged and terminals are clean and tight.
Step 3: Inspect KAM fuse (usually labeled 'ECM' or 'PCM') and replace if blown. Check for wiring damage near the ECM.
Step 4: If code persists, perform a KAM reset by disconnecting the battery for 15 minutes. Reconnect and test.
Step 5: If code returns, the ECM may be faulty. Consult a professional for ECM testing or replacement.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe for short trips, but the vehicle may experience drivability issues like rough idle or poor performance. It's best to diagnose and fix promptly to avoid potential stalling or transmission problems.
How much does it cost to fix?▼
If the issue is simply a dead battery or loose connection, cost is minimal (under $50). If the ECM needs replacement, costs range from $500 to $1,500 including labor and programming.