A Guide to the Engine Coolant Thermostat for the 2017-2024 Kia Soul
If your Kia Soul's engine is overheating, running too cold, or the check engine light is on, your thermostat could be the culprit.
- A check engine light with code P0128 is the most common sign of a failed thermostat in your Kia Soul, usually meaning it's stuck open.
- If your engine is overheating, stop driving immediately. A stuck-closed thermostat can quickly cause thousands of dollars in engine damage.
- The plastic thermostat housing can also crack and leak; inspect it carefully during the repair.
- For this critical part, choose a quality OEM or trusted aftermarket brand like Beck Arnley or Gates over the cheapest option available.
Is Your Kia Soul Thermostat Failing?
A thermostat is a wear-and-tear part. It will eventually fail. When it does, it usually gets stuck in either the open or closed position. Both scenarios cause distinct problems for your Soul's engine.
Symptoms of a Bad Thermostat
- Engine Overheats: If the thermostat is stuck closed, it traps coolant in the engine block. The coolant can't get to the radiator to cool down. You'll see the temperature gauge spike into the red. This is a critical failure that can cause serious engine damage.
- Engine Runs Too Cold: A thermostat stuck open is more common on modern cars. It allows coolant to circulate constantly, even when the engine is cold. The engine takes a very long time to warm up, or never reaches full operating temperature.
- Check Engine Light (P0128 Code): The most common code associated with a failing thermostat is P0128. This code specifically means the engine's computer has detected that the coolant temperature is below the normal regulating temperature, which strongly points to a thermostat stuck open.
- Poor Heater Performance: Your car's cabin heater uses hot engine coolant to warm the air. If the engine isn't getting hot enough because the thermostat is stuck open, you'll get lukewarm or cool air from your vents.
- Decreased Fuel Economy: An engine that runs too cold stays in its warm-up fuel cycle longer, burning more gas than necessary. 🎬 Watch: How to test for a bad thermostat and clear code P0128
Overheating is an Emergency
If your temperature gauge enters the red, pull over safely and shut off the engine immediately to prevent catastrophic damage like a warped cylinder head or blown head gasket. Do not attempt to open the radiator cap when the engine is hot.
Choosing the Right Aftermarket Thermostat
For a part this critical, quality matters more than price. While the OEM Kia thermostat is always a safe choice, high-quality aftermarket brands offer a reliable alternative. On many Kia Soul models, the thermostat is part of a larger plastic housing which should be inspected for cracks or leaks during replacement.
🎬 See this video to locate the thermostat on 1.8 and 2.0 enginesAftermarket Brand Tiers for Kia Soul
- Tier 1 (OEM Equivalent): Beck Arnley
Beck Arnley specializes in sourcing parts that match the original equipment (OE) form and fit for import vehicles. They often re-package the same part made by the original manufacturer, giving you OEM quality without the dealer markup. - Tier 2 (Trusted Aftermarket): Gates
Gates is a well-known and generally respected name in the aftermarket, especially for cooling system components. Many mechanics and experienced DIYers trust Gates for a balance of quality and value. - Tier 3 (Standard/Budget): Motorad, Calorstat
Motorad is a common brand found in many auto parts stores and offers a budget-friendly option. While many have no issues, some users in forums report mixed experiences with longevity. Calorstat is a major European OEM supplier but is less common in the North American market.
Pro Tip: When replacing the thermostat, it's a good idea to also replace the gasket and inspect the plastic thermostat housing (if equipped) for any signs of cracking or warping. Some owners also choose to replace the water pump at the same time during a major coolant service for long-term reliability.
Cost of Replacing a Kia Soul Thermostat
The cost depends on whether you do it yourself or use a repair shop. The part itself is not expensive, but labor and a coolant flush add to the total.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Thermostat | $18 - $55 |
| New OEM Thermostat/Assembly | $21 - $130 |
| Shop Labor | $121 - $177 |
| Total Professional Replacement 🎬 Save money with this step-by-step Kia Soul thermostat replacement walkthrough | $320 - $376 |
Frequently Asked Questions
What does the P0128 code mean on my Kia Soul?
P0128 means "Coolant Temperature Below Thermostat Regulating Temperature." In simple terms, your engine's computer expected the engine to warm up to a certain temperature within a certain time, and it didn't. The number one cause for this code is an engine thermostat that is stuck open.
Can I just remove the thermostat if it fails?
No. Removing the thermostat will cause the engine to run cold all the time, similar to a stuck-open failure. This leads to poor fuel economy, increased engine wear, sludge buildup, and will keep the check engine light on. The engine is designed to run at a specific temperature, and the thermostat is essential for that.
Is an OEM Kia thermostat better than aftermarket?
An OEM (Original Equipment Manufacturer) part is guaranteed to fit and perform exactly like the one your Soul came with from the factory. However, top-tier aftermarket brands like Beck Arnley or Gates are widely considered reliable and can offer significant savings. For a critical part like this, it's best to avoid the cheapest, unbranded options.
Are there any recalls for the Kia Soul thermostat?
As of early 2026, there are no specific recalls from Kia or the NHTSA for the engine coolant thermostat on the 2017-2024 Kia Soul. Always check for the latest recall information using your vehicle's VIN.
Helpful Videos
Technical Specifications
OEM Part Numbers: 255002B000 255002E000 255002E085 256002E100 256002B750
Opening temperature is typically 180°F (82°C). Part design varies between 1.6L and 2.0L engines, with some being a simple valve and others being an integrated housing assembly.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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