A Guide to the Engine Coolant Thermostat for the 2015-2020 Kia Sorento
If your Sorento's temperature gauge is acting strange or the check engine light is on, your thermostat could be the culprit.
- If your Sorento is overheating, first check if TSB ENG253 applies, as it could be a more serious, warrantied issue.
- A thermostat stuck open is the most common cause of a P0128 check engine light code.
- When replacing the thermostat, it is critical to properly bleed the cooling system to remove air pockets and prevent overheating.
- Using a quality aftermarket brand like Gates or Calorstat is a reliable and cost-effective alternative to an OEM part.
Is Your Sorento's Thermostat Failing?
A thermostat is a common wear-and-tear part. When it fails, it can get stuck in either the open or closed position, leading to distinct problems. Knowing the signs can help you diagnose the issue before it causes more serious engine damage.
Important TSB for Overheating Symptoms
Before replacing your thermostat for an overheating issue, be aware of Kia's Technical Service Bulletin (TSB) ENG253. This TSB addresses potential coolant leaks, coolant smells, and overheating in some 2015-2020 Sorento models. The warranty for these specific issues has been extended to 15 years or 180,000 miles. If your Sorento is overheating, have a dealer check if this TSB applies to your vehicle, as the problem could be more serious than a thermostat and may be covered.
Common Symptoms of a Bad Thermostat
- Engine Overheating: If the thermostat is stuck closed, coolant can't get to the radiator to cool down. This causes the engine temperature to rise quickly, which can lead to severe engine damage if not addressed immediately. 🎬 Watch: Symptoms of a thermostat stuck in the closed position.
- Engine Running Too Cold: A thermostat stuck open allows coolant to circulate constantly. This prevents the engine from reaching its proper operating temperature. You might notice the temp gauge stays low and your check engine light may come on with a P0128 code.
- Poor Heater Performance: If the engine isn't getting hot enough, the air blowing from your vents will be lukewarm at best, especially in cold weather.
- Check Engine Light: The P0128 code (Coolant Temperature Below Thermostat Regulating Temperature) is very common when the thermostat fails in the open position. 🎬 See how to diagnose P0128 and other coolant temperature codes.
Choosing the Right Aftermarket Thermostat
When replacing the thermostat, you have a choice between OEM (Original Equipment Manufacturer) and aftermarket parts. For a part like a thermostat, a high-quality aftermarket brand is often a reliable, cost-effective choice. However, some mechanics prefer the build quality of OEM parts.
Aftermarket Brand Tiers
- Premium Aftermarket (Gates, Calorstat): Gates is a well-respected name in cooling system components. Calorstat is a major OEM supplier for many car brands and is known for quality. These brands are excellent alternatives to OEM.
- Standard Aftermarket (Motorad, Beck Arnley): Motorad is a huge manufacturer of thermostats and a common option at parts stores. Beck Arnley often sources parts from various manufacturers, sometimes even the original OEM supplier, to match the original fit and function. These are solid, budget-friendly choices.
Pro Tip: Replace the Gasket
Always replace the thermostat gasket or seal when you replace the thermostat itself. Most aftermarket thermostats come with a new one in the box. This ensures a leak-free seal and prevents you from having to do the job twice.
Estimated Replacement Costs
The cost to replace the thermostat can vary based on which engine your Sorento has (2.4L or 3.3L V6) and local labor rates. Some shops may recommend replacing the entire thermostat housing assembly, which increases the part cost significantly.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Thermostat | $17 - $67 |
| New OEM Thermostat (Part Only) | $25 - $80 |
| Shop Labor | $150 - $450 |
| Total Professional Replacement | $170 - $520+ |
Frequently Asked Questions (FAQ)
Can I replace the Sorento thermostat myself?
Yes, this is a feasible DIY job for someone with intermediate mechanical skills. It requires draining the coolant and removing parts like the battery and air filter box to gain access. The most critical step is to properly bleed the cooling system after installation to remove any air pockets, which can cause overheating.
🎬 Watch this step-by-step Sorento thermostat replacement walkthrough.What is a P0128 code?
The P0128 code means the engine's computer has detected that the coolant temperature is not reaching the minimum required temperature in a set amount of time. The most common cause for this code is a thermostat that is stuck open.
Do I need to use sealant on the new thermostat gasket?
Generally, no. The new rubber gasket is designed to create a seal on its own. Adding sealant can sometimes interfere with the seal or break down over time. Simply ensure the mating surfaces on the engine and housing are perfectly clean before installing the new gasket and thermostat.
What kind of coolant should I use for my 2015-2020 Sorento?
Your Sorento requires a specific type of coolant to protect its aluminum engine components. Use a phosphate-based, silicate-free Asian vehicle coolant, often green or blue in color. Always check your owner's manual or the coolant reservoir cap for the exact specification. Using the wrong type can cause corrosion and damage.
Helpful Videos
Technical Specifications
OEM Part Numbers: 25500-2G500 25500-3C400
Standard opening temperature is typically 82°C (180°F). Always verify the correct part for your specific engine (2.4L I4 or 3.3L V6) as they may differ.
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.
- Kia Sorento:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- Is Your Sorento's Thermostat Failing?
- Important TSB for Overheating Symptoms
- Common Symptoms of a Bad Thermostat
- Choosing the Right Aftermarket Thermostat
- Aftermarket Brand Tiers
- Pro Tip: Replace the Gasket
- Estimated Replacement Costs
- Frequently Asked Questions (FAQ)
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