P2603Cooling
Coolant Pump Control Circuit High
P2603 means the coolant pump control circuit voltage is higher than expected, often from an open circuit or loss of ground.
🚗 Short trips are usually fine, but monitor temperature since the pump may not run correctly.
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🎯 Top Causes, Ranked by Likelihood
#1Open in control wiring$100-$350
A break in the circuit leaves voltage high.
#2Poor ground connection$80-$250
A missing or corroded ground raises circuit voltage.
#3Failed coolant pump$150-$600
An open pump winding causes a high reading.
#4ECM driver fault$500-$1200
The module output has failed high.
🩺 Common Symptoms
- Check engine light
- Engine temperature climbing
- Coolant pump not running
- Reduced heater performance in some models
💰 Repair Cost: DIY vs Shop
📋 Free OBD2 Code Cheat Sheet
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🔧 How to Diagnose P2603
1Inspect for open circuits in the pump wiring
2Check and clean ground connections
3Test pump winding continuity
4Verify circuit voltage with a scan tool
❓ Frequently Asked Questions
Can I drive with P2603?
Yes briefly, but watch the temperature gauge to avoid overheating damage.
What does circuit high mean?
Voltage is higher than expected, usually from an open circuit or a lost ground.
How much to fix P2603?
Typically $150-$700 depending on wiring versus pump replacement.
🔗 Related Codes
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