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Choosing the right thermostat for your Scion xB matters because an inappropriate or failing unit can cause overheating, poor cabin heat, or inefficient engine warm-up. You want a part that fits precisely, opens at the correct temperature, and provides dependable coolant flow so the engine reaches and maintains optimal operating temperature. This guide covers seven shortlisted thermostats chosen for their relevance to Scion xB owners. We evaluated each option on fitment reliability and flow characteristics, along with durability and ease of installation, to help you find a suitable replacement. Read on for what to look for and how to decide which option meets your needs.
Looking for other parts? See all Scion xB parts & accessories.
Top Picks at a Glance
| Best Reviewed A top-rated pick with lots of positive feedback | AISIN THT-011 Engine Coolant Thermostat |  |
| Most Popular A crowd favorite that many people choose with confidence | Beck/Arnley Thermostat 143-0722 |  |
| Best Quality Built to a higher standard if you want something more solid | APSG Genuine Toyota 90916-A3003 Engine Thermostat with Gasket |  |
| Best Budget The cheapest option that still gets the job done reliably | MOCA Coolant Thermostat Housing Assembly |  |
| Most Sold A high-volume bestseller chosen again and again | ROVIKE Engine Thermostat (replaces 90916-A3003 / 90916-03129) |  |
| Best Value for Money The sweet spot between price and what you get | Allmotorparts Engine Thermostat (AMP095) compatible with Toyota/Scion vehicles |  |
| Best Overall The best all-around choice for most situations | AISIN THT-019 Engine Coolant Thermostat |  |
1. AISIN THT-011 Engine Coolant Thermostat
| Manufacturer Part Number | THT-011 |
|---|---|
| OEM Part Number | 90916-03093 |
| Exterior | Machined |
| Position | Center |
This AISIN THT-011 thermostat is a direct, factory-quality replacement designed to open at the correct specified temperature and restore proper coolant flow. It is typically used when a failed thermostat causes overheating, poor cabin heat, or erratic temperature readings; replacement is straightforward during routine cooling-system work. Notable features include OE-matched form, fit, and function and machined exterior construction, which together aim to deliver consistent operating temperature and long life. Buyers will appreciate that it performs like a factory part, so radiator fan operation and engine temperature behavior return to normal without calibration. The unit does not include a gasket, so you will need to purchase the seal separately or reuse an undamaged one, which adds a small extra step. For Scion xB owners with the compatible 1NZ-FE engine, this thermostat is a reliable, low-risk fix that keeps the cooling system within OEM parameters.
Best for: Reliability-focused buyers who prioritize factory-quality replacements for routine cooling-system repairs and want a part that restores stock temperature control.
Less Ideal for: If you prefer complete installation kits that include gaskets and seals or are seeking performance-modified thermostats with different temperature ratings, this factory-matched unit is not the best choice.
- OE-matched design for correct operating temperature and reliable engine temperature control
- Machined exterior and quality manufacturing aimed at long service life
- Consistent performance restores proper radiator fan activation and coolant flow
- Well-reviewed with strong user reports of fit and function on compatible engines
- Thermostat gasket is not included and must be bought separately
- Fit depends on engine variant so verification for the specific Scion xB engine is required
Verdict A reliable, factory-matched thermostat that restores correct coolant regulation for compatible Scion xB engines, but remember to buy the gasket separately.
2. Beck/Arnley Thermostat 143-0722
| Manufacturer | Beck/Arnley |
|---|---|
| Model | Thermostat |
| Position | Center |
This Beck/Arnley thermostat is a direct-fit replacement designed to restore proper engine temperature control on compatible vehicles. It installs in the vehicle cooling housing and functions like a factory-quality thermostat, opening and closing to regulate coolant flow as the engine warms. The part is machined and described as matching OEM form, fit and function, which simplifies installation for a convenience-minded DIYer or quick shop swap. Practical benefits include generally good fitment reports and construction aimed at durability, so it can be used when the stock thermostat fails or as a routine preventative replacement. Reported issues include occasional fitment mismatches with incorrect gasket sizing and a small number of early failures, so confirm the Scion xB application before installing and have the correct gasket or seal on hand. For most owners it provides a straightforward, familiar repair experience that gets the cooling system back to normal without modifying other components.
Best for: Convenience-driven owners who prioritize a straightforward, quick replacement that closely matches factory behavior and want a part they can install without significant modification.
Less Ideal for: Drivers seeking guaranteed OEM brand-only parts or those who prefer to avoid any risk of having to source an alternate gasket or exchange a defective unit.
- Designed to match factory form, fit and function for straightforward replacement
- Machined exterior and premium materials for longer-lasting construction
- Common direct-fit option that simplifies DIY or quick shop installation
- Positive user reports of proper fitment and restored engine temperature control
- Some users report gasket mismatch requiring a separate seal purchase
- A minority of reviews mention early failures or defective units
Verdict A convenient, factory-style replacement thermostat for quick repairs on compatible vehicles, but check fitment and gasket needs before installation.
3. APSG Genuine Toyota 90916-A3003 Engine Thermostat with Gasket
| Temperature rating | 82°C (179.6°F) |
|---|---|
| Manufacturer | Toyota MotoRad |
| Brand | APSG |
| Manufacturer Part Number | 90916-A3003-MG182EA |
This thermostat is a factory-quality replacement made to the original Toyota specification and comes with the matching gasket for a proper seal. It regulates coolant flow at an 82°C opening temperature to help the engine reach and maintain its designed operating temperature, which supports efficient combustion and stable cabin heat. Installation is the same as a standard thermostat swap and is intended for routine cooling-system maintenance or when a failing thermostat causes overheating or poor warm-up. The part’s OEM fit and temperature rating mean predictable, factory-like behavior with minimal calibration or modification. Buyers should note this is a direct replacement part rather than a performance thermostat; it prioritizes correct temperature control and durability over altered warm-up or cooling characteristics. Expect straightforward fitment and reliable service when installed per factory torque and seal procedures, but do not expect improved cooling below the stock thermostat temperature.
Best for: Performance-oriented owners who want a reliable, factory-spec replacement that preserves the Scion xB's original engine temperature behavior and drivability.
Less Ideal for: Drivers seeking an aftermarket performance thermostat tuned for lower operating temperatures or increased flow for track or heavy-duty cooling needs should consider specialized alternatives.
- Factory-quality fit and construction for consistent OEM replacement performance
- Includes gasket for a proper seal and easier installation
- Rated to open at 82°C which matches factory temperature control for stable engine operation
- Made with materials sourced from USA/Japan which supports consistent manufacturing standards
- Not a high-flow or performance thermostat so it will not lower operating temperature for extra cooling
- Limited to vehicle models listed by the manufacturer rather than universal fitment
Verdict Choose this factory-quality thermostat if you want a dependable, OEM-style replacement that restores correct engine temperature control in your Scion xB rather than boosting cooling performance.
4. MOCA Coolant Thermostat Housing Assembly
| Opening Temperature | 82℃ or 179.6°F |
|---|---|
| Manufacturer | OELINE Auto Parts |
| Brand | MOCA AUTOPARTS |
This MOCA thermostat housing assembly replaces the factory coolant thermostat and housing to regulate engine temperature by opening at the specified operating point. It is typically used when a failing thermostat causes overheating, fluctuating cabin temperature, or coolant leakage. The unit matches common OEM part numbers for compatible vehicles and includes a thermostat set to an 82℃ opening point, which means it will start directing coolant to the radiator near factory operating temperature. For a DIY or budget repair on a Scion xB, the housing’s bolt pattern and connections are designed to fit the vehicle without extensive modification and can be swapped during a routine cooling system service. Practical benefits include simple installation, compatibility with factory cooling passages, and a low price that makes replacing a worn or stuck thermostat affordable. Limitations are that aftermarket fit and finish can vary compared with factory parts and buyers should confirm fitment to the Scion xB before installation; the listing does not include extended performance testing or an explicit warranty in the product details.
Best for: Budget-conscious owners looking for an affordable, do-it-yourself replacement to get the Scion xB back to normal cooling operation without paying dealer prices.
Less Ideal for: Drivers seeking a long-term OEM-equivalent or performance thermostat with documented testing and extended coverage should consider higher-end or factory-sourced parts.
- Designed to match common factory replacement part numbers for straightforward fitment
- Thermostat calibrated to open at 82℃ (179.6°F), near typical factory temperature
- Compact, complete housing assembly simplifies replacement during a cooling-system repair
- Low-cost option that reduces repair expense compared with dealer parts
- Aftermarket build quality may not exactly match factory parts in long-term durability
- Product listing does not provide extended performance testing or explicit warranty details
Verdict A low-cost, install-friendly thermostat housing assembly that makes an affordable repair choice for Scion xB owners needing a quick restoration of proper coolant control.
5. ROVIKE Engine Thermostat (replaces 90916-A3003 / 90916-03129)
| Included Components | Engine Thermostat |
|---|---|
| Power Source | Battery Powered |
| Material | Metal, Plastic |
| Connectivity Protocol | Wi-Fi |
This ROVIKE engine thermostat is a basic replacement intended to restore normal coolant flow and engine temperature regulation. It is supplied as a single thermostat and is marketed to fit a broad range of Toyota and Scion vehicles when the listed part numbers match. Installation is the same as a factory-style unit: remove the housing, swap in the new thermostat, and reassemble with a fresh gasket. Buyers can expect a straightforward, functional component made of metal and plastic that performs the single job of opening and closing at its rated temperature. Pros for everyday use are its simple, direct-replacement design and light weight that makes handling and installation easy. Limitations include fitment sensitivity — some buyers reported incorrect sizing on older vehicles — and the product is an aftermarket part rather than a factory-branded unit, which can mean variable long-term durability. For risk-averse owners planning a simple thermostat swap on a Scion xB, confirm the part number and inspect the unit against the original before final installation to avoid fit issues.
Best for: Practical, risk-averse buyers who prioritize restoring reliable engine cooling with a straightforward replacement part and prefer to match listed part numbers rather than experiment with upgrades.
Less Ideal for: Enthusiasts seeking an upgraded performance thermostat or owners unwilling to verify part numbers and compare the new unit to their original should consider alternatives or professional sourcing.
- Direct-replacement design meant to match common Toyota/Scion part numbers
- Lightweight and easy to handle during DIY installation
- Constructed from metal and plastic for basic durability
- Sold as a single, ready-to-install thermostat with simple installation steps
- Aftermarket unit so long-term durability may vary compared with factory-quality parts
- Some reviewers reported incorrect fitment on certain model years, so compatibility must be double-checked
Verdict A no-frills aftermarket thermostat that can restore proper cooling for Scion xB models if the part number and fit are carefully confirmed.
6. Allmotorparts Engine Thermostat (AMP095) compatible with Toyota/Scion vehicles
| Brand | Allmotorparts |
|---|---|
| Model Name | Engine Thermostat |
| Voltage | 3 Volts |
| Material | Stainless Steel |
| Included Components | Spring |
This Allmotorparts thermostat is a direct-style replacement that opens and closes to regulate coolant flow so the engine warms up and stays in the correct operating range. It is typically used when a vehicle is running cold, overheating, or showing erratic temperature readings; install is the same as a factory thermostat and normally requires removing the upper radiator hose and housing. Notable features called out by the maker include a stainless steel spring frame and mounting flange intended to seat the unit properly and a jiggle pin to help bleed air in vertical installations. In practice the part delivers a functional, budget-friendly swap for vehicles listed as compatible, though users report mixed fit of the included rubber gasket so you may want a spare or to reuse the OEM seal. Some buyers also noticed the housing and gasket are not as robust as factory parts and occasional slight changes in gauge reading versus OEM are reported. For a pragmatic owner wanting a low-cost replacement this unit works, but confirm fit and have a proper gasket on hand before final assembly.
Best for: Practical optimizers who prioritize reliable, low-cost repairs and are comfortable verifying fitment and swapping a gasket if needed to keep an older Scion xB running without unnecessary expense.
Less Ideal for: Buyers seeking an exact factory-quality replacement with OEM-level materials and fit, or those who prefer to avoid any post-purchase fit checks and additional gasket purchases.
- Designed to match factory fit, form, and function for listed Toyota and Scion applications.
- Stainless steel spring frame and mounting flange improve durability compared with basic stamped units.
- Includes jiggle pin for easier air bleeding in vertical installations.
- Widely compatible across many Toyota and Scion models, simplifying sourcing for older vehicles.
- Included rubber gasket may be undersized or not match OEM profile requiring replacement or reuse of the original.
- Aftermarket housing and components feel less heavy-duty than some factory thermostats, which may affect long-term durability.
Verdict A budget-friendly, functional replacement thermostat for Scion xB owners who want a practical repair but should double-check the gasket and fit before final installation.
7. AISIN THT-019 Engine Coolant Thermostat
| Included Components | thermostat |
|---|---|
| Voltage | 12 Volts |
| Material | Alloy Steel, Plastic |
| Mounting Type | Direct Engine Mount |
| Position | Inside |
The AISIN THT-019 is a direct-fit replacement thermostat that regulates engine coolant flow to maintain the correct operating temperature. Installed in the thermostat housing, it opens at the specified temperature and modulates flow as the engine warms, which helps the engine reach and hold operating temperature reliably and restores cabin heat performance. Notable points are its manufacturer-matched operating temperature and OEM-level fitment, which reduce the risk of overcooling or overheating compared with generic units. Typical use is a routine replacement during cooling-system service or to correct poor warm-up behavior. Practical benefits include predictable thermal behavior, consistent opening across the temperature range, and durable construction intended for long life. Limitations are that the gasket is sold separately and fitment depends on the specific Scion xB year and engine, so confirmation of compatibility before purchase is necessary.
Best for: A balanced all-round buyer who wants a reliable, factory-quality replacement that restores correct engine temperature and cabin heat without fuss, prioritizing long-term dependability over lowest cost.
Less Ideal for: Buyers seeking ultra-budget aftermarket options or those who need a thermostat for a different vehicle model or nonstandard engine configurations should look elsewhere.
- Manufacturer-matched operating temperature for predictable warm-up and cooling
- Built to factory-quality form, fit, and function for direct replacement
- Durable mixed-metal and plastic construction intended for long service life
- Consistent opening behavior that restores proper cabin heat and engine temp control
- Thermostat gasket is not included and must be purchased separately
- Requires verifying year-and-engine fitment for the Scion xB before installing
Verdict Aisin's THT-019 is a dependable, factory-matched replacement thermostat for Scion xB owners who want OEM-like temperature control and durable construction.
Choosing the Right Scion xB Thermostat: Key Factors to Consider
Opening Temperature
The thermostat's opening temperature determines when coolant begins circulating through the engine and radiator. A thermostat rated too low can cause the engine to run cold, reducing fuel efficiency and cabin heat, while one rated too high can delay coolant flow and increase the risk of overheating.
Choose a thermostat with the factory-specified opening temperature or an approved close tolerance. Consistency in the opening temperature matters because even small deviations can change warm-up time and engine combustion characteristics. Look for units that state their temperature rating clearly so you can match the original equipment specification.
Flow Rate and Valve Operation
How quickly and fully the valve opens affects coolant circulation at various engine loads. A properly functioning valve moves to an appropriate aperture as temperature rises, providing steady flow without restriction or abrupt surges that could stress the cooling system.
Consider thermostats that provide smooth, proportional opening and closing behavior. This reduces temperature oscillations and helps maintain a stable engine temperature under varying driving conditions. Flow characteristics also impact heater core performance and defogging capability.
Fitment and Housing Compatibility
Correct fitment ensures the thermostat seats properly in the housing and interfaces correctly with temperature sensors and coolant passages. Poor fit can lead to bypassed flow, incorrect sensor readings, or mechanical interference that causes leaks or premature failure.
Verify the thermostat physical dimensions, flange style, and sensor ports against the Scion xB housing design. A unit that matches the original geometry will ease installation and reduce the need for additional gaskets or modifications. Proper sealing surfaces and alignment are critical for reliable long-term operation.
Materials and Corrosion Resistance
Thermostats are exposed to coolant and varying temperatures, so materials must resist corrosion and degradation. Choices include stainless components, high-temperature alloys, and corrosion-resistant coatings that extend service life and prevent sticking or swelling.
Assess the construction of the valve, spring, and housing flange. Materials that stand up to coolant additives and temperature cycles reduce the risk of the thermostat seizing open or closed. Durable materials also lower the likelihood of metal particles or debris contaminating the cooling system.
Seal Quality and Gasket Design
A reliable seal prevents coolant leakage at the thermostat housing interface. Gasket integrity and seal materials influence resistance to heat, pressure, and coolant chemistry. A poor seal can lead to external leaks and a drop in system pressure, reducing cooling efficiency.
Look for thermostats that include purpose-designed gaskets or a proven sealing surface compatible with the Scion xB housing. Consider the resilience of the gasket material to repeated thermal cycling, as brittle or compressed gaskets are common failure points. Proper sealing reduces the chance of a thermostat housing seal leak.
Ease of Installation and Serviceability
Thermostat replacements are often performed during routine maintenance, so straightforward installation reduces labor time and the risk of installation errors. Features like clear orientation markings, included gaskets, and compatible sensor ports simplify the process.
Consider how easily you can access the housing, whether any hoses or brackets must be removed, and if the unit requires special tools. A design that enables predictable seating and torquing reduces the chance of post-installation leaks or misalignment. Ease of service also matters if you plan to test a thermostat or perform routine inspections yourself.
FAQ
What are common signs of a bad thermostat in my Scion xB?
Common signs include engine overheating, temperature gauge readings that swing widely, or the engine taking longer than usual to reach operating temperature. You might also notice weak heater performance or coolant leaks around the thermostat housing. These symptoms often indicate the thermostat is stuck closed, stuck open, or the housing seal is failing.
How do I test a thermostat to see if it is working correctly?
A typical test involves observing temperature behavior during warm-up and checking for coolant flow once the engine reaches operating temperature. Some users perform a bench test by heating the thermostat in water and checking the opening temperature against the rated spec. In-vehicle checks also include feeling upper and lower radiator hoses for temperature change as the engine warms.
How long does a thermostat usually last before it needs replacement?
Thermostat lifespan varies with materials, coolant condition, and driving habits, but many last several years under normal use. Exposure to corrosion, contaminated coolant, or frequent extreme temperature cycles can shorten service life. Regular cooling system maintenance and timely replacement of degraded gasket seals can extend thermostat longevity.
Can a failing thermostat cause the engine to overheat quickly?
Yes, if the thermostat is stuck closed or opens late, coolant circulation to the radiator is restricted, which can lead to rapid temperature rise under load. Overheating risk is higher during slow or stop-and-go traffic and when towing or climbing grades. Addressing thermostat issues promptly reduces the chance of engine damage.
Should I replace the thermostat housing gasket when changing the thermostat?
It is generally advisable to inspect and often replace the housing gasket when installing a new thermostat. Gaskets can become compressed, brittle, or contaminated over time, leading to leaks. Installing a fresh, compatible gasket helps ensure a reliable seal and reduces the likelihood of a thermostat housing seal leak after service.
Does replacing the thermostat fix heater core problems?
Replacing a thermostat can resolve heater issues if the root cause is improper engine warm-up or restricted coolant flow. If the heater core itself is clogged, leaking, or the blower system has faults, a new thermostat may not solve those problems. It often depends on whether the thermostat was preventing proper coolant circulation through the heater core.
How We Chose the Best Scion xB Thermostat
We focused on items that match the Scion xB mechanical and cooling system specifications to ensure direct fitment and proper function. Key evaluation criteria included thermostat opening temperature tolerance, valve flow rate under normal operating pressures, material and corrosion resistance, and compatibility with the Scion xB thermostat housing and sensors. We also weighed durability and manufacturer quality control, plus how straightforward the unit is to install for routine engine thermostat replacement jobs. Units that required extensive modification, questionable fitment, or had inconsistent performance data were excluded. We did not consider parts without clear temperature-rating information or those lacking specification transparency. The final list emphasizes accurate fitment, predictable operating temperature, reliable flow characteristics, and long-term sealing integrity.
Our full evaluation process is outlined in our review methodology.
Conclusion
Prioritize correct opening temperature and verified fitment when choosing a replacement thermostat for a Scion xB, since those factors most directly affect warm-up behavior and overheating risk. Also weigh valve flow characteristics, material durability, and seal quality to minimize leaks and ensure consistent engine temperature control. Balancing ease of installation against long-term reliability will help you get dependable performance. If you are unsure about fitment or testing procedures, consult a mechanic or reference vehicle-specific documentation to confirm the right specifications before purchasing.
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