Internal Control Module Memory Signal Performance
The U0603 code means the vehicle's onboard diagnostic system has detected: Internal Control Module Memory Signal Performance. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $800
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Multiple warning lights on
- Vehicle running rough
- Intermittent stalling
- Stored codes cannot be cleared
Probable Causes (Ranked by Likelihood)
- ECM internal memory corruption Very High
- Low battery voltage causing memory errors High
- Software update needed Moderate
- ECM hardware failure Low
Step-by-Step Diagnostic Procedure
-
Check battery voltage and charging system
-
Attempt ECM software update
-
Clear codes and monitor for recurrence
-
Test ECM with manufacturer diagnostic tool
Frequently Asked Questions
Can I drive with U0603?
Check the severity. If it affects safety systems like stability control or braking, limit driving to short distances. Comfort features like heaters or parking assist are safe to drive with.
What causes U0603?
Most commonly a faulty internal control module memory or damaged wiring in the communication circuit to that module.
How much does it cost to fix U0603?
Typical repair costs range from $200 - $800 depending on whether the module or just wiring needs repair.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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