Genuine Hyundai 25500-2B000 Thermostat Assembly 82°C/180°F | 1.6L Accent, Veloster, Elantra

Genuine Hyundai 25500-2B000 Engine Coolant Thermostat Assembly

Temperature gauge barely climbs, the engine takes forever to warm up, fuel consumption creeps up — and the scanner shows code P0128? That is the signature of a thermostat stuck open. Stuck closed is worse: the engine overheats while the upper radiator hose stays cold.

The Hyundai 25500-2B000 is the genuine thermostat assembly for Hyundai's 1.6L Gamma GDI and T-GDI engine family. It opens at the factory-specified 82°C (180°F), restoring proper warm-up behavior and stable operating temperature.

OEM Part Numbers

• 25500-2B000
• 255002B000

Aftermarket Cross Reference

• MAHLE TX 348 82D
• Gates 34802
• AISIN THYK-803
• Vernet / Calorstat TH6949.82J
• Beck/Arnley 143-0900
• MOTORAD 726-180

Common Symptoms of a Failed Thermostat

• Stuck open: engine takes very long to warm up
• Stuck open: temperature gauge reads low while driving
• Stuck open: increased fuel consumption
• Stuck open: check engine light with code P0128 (coolant temperature below thermostat regulating temperature)
• Stuck closed: engine overheats
• Stuck closed: upper radiator hose stays cold while the engine is hot

Product Highlights

• ✔ Genuine Hyundai OEM thermostat assembly — the same part your dealer installs
• ✔ Factory opening temperature: 82°C / 180°F
• ✔ Common repair for code P0128 and slow warm-up complaints
• ✔ Built for the 1.6L Gamma GDI / T-GDI engine family
• ✔ Restores normal warm-up, heater performance and stable coolant temperature

Condition

New, Genuine Hyundai OEM part

Product Type

Engine Coolant Thermostat Assembly

Function

The thermostat regulates coolant flow between the engine and the radiator. It stays closed while the engine is cold for a fast warm-up, then begins to open at 82°C (180°F) to hold the engine at its designed operating temperature. A thermostat that no longer opens or closes at the correct temperature causes slow warm-up, code P0128, or overheating.

Compatible Vehicles

Applications are Hyundai models with the 1.6L Gamma GDI / T-GDI engine family:

Model	Years / Engine
Hyundai Accent	2012–2019, 1.6L
Hyundai Veloster	2012–2021, 1.6L
Hyundai Elantra / Elantra GT	1.6L applications
Hyundai Kona	1.6L applications
Hyundai Sonata	1.6T Eco
Hyundai Tucson	1.6T

Cross-reference catalogs also list the same thermostat for select Kia 1.6L applications.

Important: Please verify fitment with your VIN before ordering.

Package Contents

• 1 × Genuine Hyundai 25500-2B000 Thermostat Assembly (flange seal comes integrated on the assembly, as pictured)

Technical Specifications

Brand	Hyundai
Manufacturer	Hyundai Motor Company
Part Number	25500-2B000
Alternate Part Number	255002B000
Seller SKU	Hyundai_25500-2B000
Product Type	Engine Coolant Thermostat Assembly
Opening Temperature	82°C / 180°F
Engine Family	1.6L Gamma GDI / T-GDI
Weight (packaged)	Approx. 0.4 lb
Condition	New

Warranty

Manufacturer warranty may vary by supplier, seller, and region. Please contact us before purchase if warranty confirmation is required.

Installation Video

FAQ

What is the opening temperature of this thermostat?

82°C / 180°F — the factory specification for the 1.6L Gamma engine family, confirmed by the matching aftermarket cross references (Gates 34802, AISIN THYK-803, Calorstat TH6949.82J).

Will this fix code P0128?

P0128 means the coolant temperature stays below the thermostat regulating temperature, and a stuck-open thermostat is its most common cause. Confirm the diagnosis (coolant level, temperature sensor) before replacing.

How do I know if my thermostat is stuck closed?

The engine overheats while the upper radiator hose stays cold — coolant is not circulating through the radiator. Stop driving and replace the thermostat.

Will it fit my 1.6L Hyundai?

It is used across the 1.6L Gamma GDI / T-GDI family — Accent, Veloster, Elantra/Elantra GT, Kona, Sonata 1.6T Eco, Tucson 1.6T. Year ranges vary by model, so please verify with your VIN before ordering.

Is this a genuine Hyundai part?

Yes. This is the genuine Hyundai OEM thermostat assembly, part number 25500-2B000.

Which aftermarket numbers cross to this thermostat?

Verified cross references: MAHLE TX 348 82D, Gates 34802, AISIN THYK-803, Vernet/Calorstat TH6949.82J, Beck/Arnley 143-0900 and MotoRad 726-180.