Replacing the thermostat in a 2015 Jeep Wrangler is a task many owners can handle themselves. It’s a key maintenance job because a faulty thermostat can cause engine overheating, poor fuel efficiency, or even engine damage.
If your Jeep is running too hot or too cold, or you see the check engine light with a coolant temperature code, it’s likely time for a change.
With a few tools and some patience, you can restore your Jeep’s cooling system and enjoy smoother driving.
What You Need Before Starting
Changing the thermostat requires some preparation. Gather these items:
- New thermostat (OEM or high-quality aftermarket)
- Thermostat gasket (usually included)
- Ratchet and socket set (8mm or 10mm)
- Screwdriver
- Drain pan
- Coolant (check your owner’s manual for the correct type)
- Clean rags
- Safety gloves and glasses
It’s smart to work on a cold engine. Hot coolant can cause burns, so let your Jeep sit for a few hours before starting.
Step-by-step Thermostat Replacement
Follow these steps to change the thermostat in your 2015 Jeep Wrangler:
1. Disconnect The Battery
For safety, remove the negative terminal from the battery using a wrench.
2. Drain The Coolant
Place the drain pan under the radiator. Open the radiator drain valve and let the coolant flow out.
If you plan to reuse coolant, keep it clean.
3. Locate The Thermostat Housing
The housing is found where the upper radiator hose connects to the engine. It’s usually a metal cover held by two bolts.
4. Remove The Radiator Hose
Loosen the hose clamp with a screwdriver and pull the hose off the housing. Some coolant may spill, so keep the pan handy.
5. Remove The Thermostat Housing Bolts
Use your socket set to remove the bolts. Take care not to drop them into the engine bay.
6. Take Out The Old Thermostat
Lift the housing and remove the old thermostat. Note its orientation most thermostats fit with the spring side facing the engine.
7. Clean The Housing And Engine Surface
Use a rag to wipe away old gasket material or debris. A clean surface helps prevent leaks.
8. Install The New Thermostat And Gasket
Place the new thermostat in the same position as the old one. Set the gasket in place, making sure it’s aligned correctly.
9. Reattach The Housing And Hose
Bolt the housing back on, tighten evenly, and reconnect the radiator hose. Secure the hose clamp.
10. Refill Coolant
Pour coolant into the radiator until full. If using old coolant, filter it first.
11. Reconnect The Battery
Attach the negative terminal.
12. Start The Engine And Check For Leaks
Run the Jeep for a few minutes, watching for leaks around the housing and hose. Add more coolant if needed.
13. Check Engine Temperature
Monitor the dashboard gauge. The engine should warm up normally and stay at the proper temperature.
Thermostat Types And Compatibility
The 2015 Jeep Wrangler uses a thermostat rated around 203°F (95°C) for optimal engine performance. There are two main types:
- OEM thermostats: Designed to match factory specs. Reliable and easy to install.
- Aftermarket thermostats: May offer different temperature ratings. Check compatibility for your engine model.
Here’s a comparison of OEM vs aftermarket options:
| Type | Temperature Rating | Warranty | Price Range |
|---|---|---|---|
| OEM | 203°F | 1 year | $30–$60 |
| Aftermarket | 180–210°F | 6 months–2 years | $20–$50 |
Always check the thermostat’s temperature rating and fitment for the 2015 Wrangler’s engine (3.6L Pentastar V6).
Common Mistakes And How To Avoid Them
Many beginners make errors when replacing thermostats:
- Not draining coolant fully: This causes spills and mess.
- Using wrong gasket: Leads to leaks.
- Overtightening bolts: Can crack the housing.
- Wrong thermostat orientation: Engine may overheat or run cold.
Double-check the parts and follow each step slowly. If unsure, watch video tutorials or consult your Jeep’s manual.
Signs Of A Failing Thermostat
Recognizing a bad thermostat can save your engine:
- Erratic temperature gauge readings
- Heater not working
- Coolant leaks under the Jeep
- Check engine light with P0128 code
If you notice these, a replacement is likely needed.
Estimated Cost And Time
Most Jeep owners spend $50–$80 for parts and coolant. The job takes about 1–2 hours for a first-timer. Professional shops may charge $150–$250, but DIY is cost-effective.
Here’s a quick breakdown:
| Task | DIY Cost | Shop Cost | Time Required |
|---|---|---|---|
| Parts (thermostat + gasket) | $30–$60 | Included | — |
| Coolant | $20–$30 | Included | — |
| Labor | — | $100–$200 | 1–2 hours |
Helpful Tips For A Smooth Job
- Buy quality parts: Cheap thermostats may fail quickly.
- Have extra coolant: Topping up is common after air pockets release.
- Check for air bubbles: After refilling, let the engine run and open the radiator cap briefly to release trapped air.
- Dispose of old coolant properly: It’s toxic—never pour it down the drain.
- Clean up spills quickly: Coolant is slippery and dangerous for pets.
Many new DIYers miss that air pockets can cause overheating even after replacing the thermostat. Another overlooked tip is to check the condition of the radiator hose. If it’s old or cracked, replace it during the job.
How Often Should I Change The Thermostat In My Jeep Wrangler?
Most thermostats last 5–7 years or 60,000–100,000 miles. Replace if there are symptoms or during major cooling system repairs.
Can I Drive With A Bad Thermostat?
It’s risky. A stuck thermostat can cause engine overheating or poor performance. Driving for long periods may damage the engine.
What Type Of Coolant Does The 2015 Jeep Wrangler Need?
Use HOAT (Hybrid Organic Acid Technology) coolant, usually orange or yellow. Always check your owner’s manual for exact specifications.
Is It Necessary To Bleed The Cooling System After Changing The Thermostat?
Yes. Bleeding removes air pockets that can cause overheating. Run the engine with the radiator cap off and add coolant until bubbles stop.
Where Can I Find Official Jeep Wrangler Repair Guides?
The best source is the Jeep official website or trusted platforms like AutoZone. These guides offer step-by-step instructions and diagrams.
Changing your thermostat is a straightforward process with the right tools and careful steps. Keeping your Jeep’s cooling system in top shape will help avoid costly repairs and keep your Wrangler running strong for years to come.
