p0128
Moderate
Genesis · SUVs
Coolant Thermostat Malfunction
Quick Answer
Error code P0128 on your Genesis SUVs means: Coolant Thermostat Malfunction. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Likely Causes
How to Fix It
1
Allow engine to warm up and monitor coolant temperature
2
Check if radiator fan cycles properly
3
Test coolant temperature sensor resistance
4
Verify thermostat housing condition
5
Monitor cooling system pressure
Pro Tip
This fix requires some technical knowledge. If you're unsure about any step, consider contacting support or a qualified technician.
Parts You May Need
Thermostat assembly
Coolant temperature sensor
Engine coolant
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