What this code means

The ECU detected that the engine cooling system is not operating within expected parameters. The coolant temperature is not reaching or maintaining the expected operating range within the allotted time.

Symptoms

• Check Engine Light
• Engine running cold
• Poor heater output
• Reduced fuel economy
• Higher emissions

Common causes

• Thermostat stuck open
• Coolant temperature sensor fault
• Low coolant level
• Cooling fan running constantly
• Coolant leak causing slow warm-up

Diagnostic steps

1. Check coolant level and condition
2. Monitor coolant temperature rise during warm-up with scan tool
3. Test thermostat operation
4. Test coolant temperature sensor
5. Check for coolant leaks

Repair notes

Replace the thermostat if the engine is not reaching operating temperature.

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