p0128
Moderate
Hyundai · SUVs
Coolant Thermostat (Coolant Temp Regulation) Malfunction
Quick Answer
Error code P0128 on your Hyundai SUVs means: Coolant Thermostat (Coolant Temp Regulation) Malfunction. This is usually fixable — see the step-by-step guide below.
Affected Models
Applies to all models
Ioniq 5 Limited 2024Ioniq 5 N 2024Ioniq 5 SE Long Range 2024Ioniq 5 SE Standard Range 2024Ioniq 5 SEL 2024Kona Limited 2024Kona N Line 2024Kona SEL 2024Palisade Calligraphy 2024Palisade Limited 2024Palisade SE 2024Santa Fe Calligraphy 2024Santa Fe Limited 2024Santa Fe SE 2024Santa Fe XRT 2024Tucson Limited 2024Tucson N Line 2024Tucson SE 2024Tucson XRT 2024Ioniq 5 SE 2024Kona SE 2024Kona Electric SE 2024Palisade SEL 2024Santa Cruz SE 2024Santa Fe SEL 2024Santa Fe Hybrid SEL 2024Tucson SEL 2024Tucson Hybrid SEL 2024Venue SE 2024
Likely Causes
How to Fix It
1
Check coolant level and top off if low
2
Monitor coolant temperature gauge during warm-up
3
Test coolant temperature sensor resistance
4
Check coolant circulation at radiator hose
5
Replace thermostat if stuck
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
Coolant temperature sensor
Engine coolant
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