Nissan Altima Engine Coolant Thermostat Guide (2002-2014)
Understanding the common failure points and choosing the right replacement thermostat for your Altima's engine.
- Many 2.5L Altimas from this era use two thermostats; it's best to replace both at once.
- A stuck-closed thermostat causes overheating (critical), while a stuck-open one causes no heat and poor MPG (moderate).
- For best results, choose an OEM-equivalent brand like Aisin or a reputable aftermarket brand like Gates.
- If you have a 2013-2014 model, inspect the plastic thermostat housing for cracks, as it was subject to a recall.
Is Your Altima's Thermostat Failing?
A thermostat is a wear item. After thousands of heating and cooling cycles, it can fail in one of two ways: stuck open or stuck closed. A thermostat stuck closed is the most dangerous type of failure, as it will cause the engine to overheat quickly, leading to serious and expensive damage. A thermostat stuck open is less critical but will cause its own set of problems, including poor heater performance and reduced fuel economy.
Important: Your Altima May Have Two Thermostats
Many 2002-2014 Nissan Altimas, especially those with the 2.5L 4-cylinder engine, are equipped with two separate thermostats (sometimes called a thermostat and a water control valve). They work together to control engine temperature. If you are experiencing thermostat-related symptoms, it is highly recommended to replace both parts at the same time to ensure a complete and lasting repair. Always verify the number of thermostats your specific engine requires before ordering parts.
Choosing the Right Aftermarket Thermostat
When it comes to a critical part like the thermostat, quality matters. While an OEM part from Nissan is always a safe choice, several aftermarket brands offer excellent quality, sometimes from the same factory that supplies Nissan.
Brand Quality Tiers
- OEM-Equivalent (Best Choice): Brands like Aisin are often the original equipment manufacturer for Nissan. Choosing Aisin is like getting the dealer part without the dealer price. Beck Arnley is also a strong choice, as they often repackage the original OEM part in their own box.
- Reputable Aftermarket (Good Choice): Gates is a well-known and generally trusted name in cooling system parts. While some enthusiasts debate if their quality is the same as it once was, a Gates thermostat is a solid and reliable option for most owners.
- Economy & Mixed Reviews: Brands like Motorad are widely available and often have the lowest price. However, owner experiences are very mixed, with some reporting premature failures. Their "Fail-Safe" thermostats, designed to lock in the open position if they fail, are often avoided by mechanics due to reliability concerns.
- Performance Option: Brands like Mishimoto offer high-performance thermostats, which may open at a lower temperature. These are typically only necessary for highly modified or track-driven vehicles.
Pro Tip: Always replace the thermostat gasket or seal when installing a new thermostat, even if it looks okay. Many quality thermostat kits include a new one. Also, this is the perfect time to drain and replace your engine coolant with the correct Nissan Blue (L255N) or an equivalent Asian vehicle formula.
Known Issues for 2013-2014 Models
While no recalls exist for the thermostat itself, Nissan issued a recall for the thermostat housing on some 2013-2018 Altima models. The plastic housing could crack, leading to a sudden coolant leak and potential engine overheating. If you have a 2013 or 2014 model, it is wise to inspect the thermostat housing carefully for any signs of cracks or leaks when replacing the thermostat.
| Part Type | Estimated Cost |
|---|---|
| New Aftermarket Thermostat | $14 - $100 |
| New OEM Thermostat (Dealer) | $40 - $80 (per thermostat) |
| Shop Labor for Replacement | $150 - $300 |
Frequently Asked Questions
Do I really need to replace both thermostats on my 2.5L Altima?
Yes. It is strongly recommended. The labor to access the area is the same, and if one has failed, the other is likely near the end of its service life. Replacing only one can lead to having to do the entire job again in the near future.
My temperature gauge is fluctuating wildly. Is that the thermostat?
Yes, an erratic temperature gauge that swings from cool to normal or suddenly spikes is a classic symptom of a failing thermostat that is sticking or opening and closing incorrectly.
Can I do this replacement myself?
For many DIYers, this is a manageable job. It requires draining the coolant and removing the air intake box for access. The difficulty is moderate, mainly due to the tight space. If your Altima has two thermostats, the second one can be more challenging to reach.
What's the difference between a 180°F and 203°F thermostat?
This is the temperature at which the thermostat begins to open. You should always use the temperature specified for your vehicle's engine. Using a thermostat with the wrong temperature can affect engine performance, fuel economy, and emissions.
Helpful Videos
Technical Specifications
Temperature ratings vary by engine and year, commonly 180°F or 203°F. Many 2.5L QR25DE engines use a dual-thermostat system (one main thermostat, one water control valve). Always verify the correct temperature and quantity for your specific vehicle.
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.
- Nissan Altima: