Thermostat / Temperature Sensor

Water Temperature Sensor

OE Match replacement water temperature sensor for Porsche Boxster 986 and Porsche 996 models.

Fits:

• Porsche Boxster 986 2.5L 1997-99
• Porsche 996 C2 3.4L 1997-08/01
• Porsche 996 C4 3.4L 1997-08/01
• Porsche 996 TURBO 2000-05
• Porsche 996 GT3 MKI 1999-02

Diagram Ref No 29

This essential engine management component monitors coolant temperature and sends information to the engine control unit (ECU), helping regulate fuel delivery, engine performance and cooling system operation.

Designed as an original-style replacement, it helps restore accurate temperature monitoring and reliable engine operation when the original sensor becomes faulty.

What Does the Water Temperature Sensor Do?

The sensor measures engine coolant temperature and sends an electrical signal to the ECU.

This information helps the engine management system adjust fuel mixture, cold-start operation and other temperature-dependent functions, ensuring efficient engine performance.

Why Does It Fail?

Over time, repeated heating and cooling cycles, moisture and electrical deterioration can affect sensor accuracy.

Common problems include:

• Internal sensor failure
• Corroded or damaged electrical connections
• Incorrect or fluctuating temperature readings
• Intermittent electrical signals
• Damage caused by coolant leaks or overheating

When Should It Be Replaced?

Replacement may be necessary if you experience:

• Incorrect or erratic engine temperature readings
• Difficult cold starting or poor warm-up performance
• Increased fuel consumption
• Engine management warning lights
• Cooling fan operation that appears abnormal

Before replacement, check the coolant level, electrical connector, wiring and relevant fault codes to confirm the cause.

Additional 996 variants may have different sensor arrangements. Confirm compatibility using the original part number or vehicle VIN before ordering.

Porsche Boxster 986 & 911 996 Coolant Temperature Sensors

The coolant temperature sensor plays an important role in the engine management system of water-cooled Porsche models, providing accurate temperature information for efficient engine operation.

A faulty sensor can cause incorrect temperature readings, poor cold starting, increased fuel consumption and engine management faults.

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99660640501

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Water Thermostat Housing With Thermostat Insert And Gasket.
Standard Temperature 83 °C
The OE Match Water Thermostat Housing with Thermostat Insert and Gasket is a complete replacement cooling system assembly designed to regulate engine coolant flow and maintain the optimum operating temperature. Supplied with a standard temperature 83°C thermostat insert and sealing gasket, this OE-quality assembly provides a direct replacement solution for worn or faulty thermostat housings.

Fits:

• Porsche Boxster 986 2.5L 1997-99
• Porsche Boxster 986 2.7L 1999-02
• Porsche Boxster S 986 3.2L 1999-02
• Porsche Boxster 986 2.7L 2003-04
• Porsche Boxster S 986 3.2L 2003-04
• Porsche Boxster 987 2.7L 2005-08/08
• Porsche Boxster 987 S 3.2/3.4L 2005-08/08
• Porsche 996 C2 3.4L 1997-08/01
• Porsche 996 C4 3.4L 1997-08/01
• Porsche 996 C2 3.6L 09/01-2005
• Porsche 996 C4 3.6L 09/01-2005
• Porsche 996 C4S 3.6L 09/01-2005
• Porsche 997 MK1 Carrera 2 3.6L 2005-08
• Porsche 997 MK1 Carrera 2S 3.8L 2005-08
• Porsche 997 MK1 Carrera 4 3.6L 2005-08
• Porsche 997 MK1 Carrera 4S 3.8L 2005-08
• Porsche Cayman 2.7L 987C 2006-08
• Porsche Cayman S 3.4L 987C 2005-08  

Diagram Ref No 5

Manufactured to OE specifications for fit, durability and cooling performance, the assembly features a precision-engineered thermostat housed within a robust, heat-resistant housing. The thermostat remains closed during engine warm-up to allow the engine to reach its correct operating temperature quickly before opening at approximately 83°C to allow coolant to circulate through the radiator, preventing overheating while maintaining efficient engine operation.

What This Product Does:

• Regulates coolant flow throughout the engine cooling system.
• Opens at approximately 83°C to maintain the correct engine operating temperature.
• Speeds up engine warm-up after a cold start.
• Prevents engine overheating during normal operation.
• Improves fuel efficiency by maintaining optimum engine temperature.
• Supports efficient cabin heater performance.
• Includes a new housing, thermostat insert and gasket for a complete installation.

Symptoms Of Wear Or Failure:

• Engine overheating.
• Engine taking an unusually long time to reach operating temperature.
• Fluctuating temperature gauge readings.
• Coolant leaks around the thermostat housing.
• Low coolant level warnings.
• Poor cabin heater performance.
• Engine running too hot or too cold.
• Illuminated engine or cooling system warning lights.
• Visible cracks or damage to the thermostat housing.
• Increased fuel consumption caused by incorrect engine temperature.

Why Replacement Matters:

• The thermostat and housing are essential components of the engine cooling system and are continuously exposed to heat cycles, coolant pressure and engine vibration. Over time, the thermostat can stick open or closed, while the housing and seals may deteriorate or develop leaks.
• A thermostat that remains closed can quickly cause engine overheating, while one that remains open prevents the engine from reaching its correct operating temperature. Both conditions reduce engine efficiency, increase fuel consumption and can lead to premature engine wear. Coolant leaks from a damaged housing can also result in coolant loss and severe engine damage if left unresolved.
• Replacing the complete thermostat housing assembly with a new thermostat insert and gasket restores correct coolant regulation, improves engine efficiency and protects against overheating. An OE Match replacement provides factory-style fitment, reliable temperature control and long-lasting durability, helping maintain the performance, reliability and longevity expected from your Porsche.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610601361

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Water thermostat insert
The Genuine Porsche Water Thermostat Insert (Part Number: 99610612554) is an original equipment engine cooling system component. This temperature-sensitive thermostat insert regulates the flow of engine coolant between the engine and radiator, helping maintain the correct operating temperature under varying driving conditions. When the engine is cold, the thermostat restricts coolant circulation through the radiator to allow faster warm-up. As the engine reaches its operating temperature, the thermostat opens to permit coolant flow through the cooling system, helping prevent overheating.

Fits:
Porsche 986 Boxster 2.5L / 2.7L / 3.2L 1997 - 2004 
 * engine code:  9620 / 9621 / 9622 /  9623 /  9624

Porsche 987 Boxster  >>31.07.2005
 * engine code:  9625 / 9626

Porsche 987C Cayman 2006 - 2008
 * engine code:  9720 / 9721 / 9722

Porsche 996 Carrera 3.4L / 3.6L 1998 - 2005
 * engine code:  9601 / 9602 / 9603 / 9604

Porsche 996 GT3 3.6L 2000 - 2000
 * engine code: 9676

Porsche 997 Carrera 3.6L / 3.8L 2005 - 2008
 * engine code: 9701 / 9605

Diagram Ref No 6.

Manufactured to Porsche's original specifications, this genuine replacement thermostat offers precise fitment, reliable temperature regulation and dependable cooling system performance.

Ideal for replacing a faulty, sticking or damaged original thermostat during cooling system repairs, water pump replacement or preventative maintenance.

Previous Porsche Part Numbers: 99610612552 / 99610612553

What Does This Part Do? – Functions

• Temperature Regulation: Helps maintain the engine's correct operating temperature.
• Coolant Flow Control: Regulates coolant circulation between the engine and radiator.
• Faster Engine Warm-Up: Restricts radiator flow when the engine is cold.
• Overheating Protection: Allows coolant circulation through the radiator as temperatures rise.
• Original Fitment: Maintains Porsche factory cooling system specifications.

Why Replace This Part?
Over time, the thermostat can become worn, stuck or faulty due to repeated temperature changes, ageing and coolant contamination. A thermostat stuck closed may cause engine overheating, while one stuck open can prevent the engine from reaching its normal operating temperature.

Replacing a faulty thermostat with a genuine Porsche component helps restore accurate coolant flow control, maintain stable engine temperatures and protect the cooling system from unnecessary strain.

When to Replace This Part?

• Engine Overheating: Temperature rising above normal operating levels.
• Slow Warm-Up: Engine taking too long to reach operating temperature.
• Temperature Fluctuations: Irregular or inconsistent coolant temperature readings.
• Sticking Thermostat: Thermostat failing to open or close correctly.
• Cooling System Repairs: During thermostat housing or water pump servicing.

Where Does It Fit on the Car?
Location: Engine cooling system – thermostat housing / water pump assembly.

The thermostat insert is installed inside the engine's thermostat housing, near the water pump assembly.

It controls the flow of coolant through the cooling circuit, opening and closing according to coolant temperature to maintain efficient engine cooling.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610612554

The product you are viewing cross references to these numbers

Water Thermostat Insert
High-quality Wahler water thermostat insert for selected Porsche Boxster, Cayman and 911 models, corresponding to Porsche OE reference 99610612554. The thermostat is a critical part of the engine cooling system, regulating the flow of coolant between the engine and radiators according to operating temperature. During cold start, the thermostat remains closed to help the engine reach its correct operating temperature efficiently. As coolant temperature rises, it opens to allow circulation through the radiator system and control engine temperature.

Fits:
Porsche 986 Boxster 2.5L / 2.7L / 3.2L 1997 - 2004 
 * engine code:  9620 / 9621 / 9622 /  9623 /  9624

Porsche 987 Boxster  >>31.07.2005
 * engine code:  9625 / 9626

Porsche 987C Cayman 2006 - 2008
 * engine code:  9720 / 9721 / 9722

Porsche 996 Carrera 3.4L / 3.6L 1998 - 2005
 * engine code:  9601 / 9602 / 9603 / 9604

Porsche 996 GT3 3.6L 2000 - 2000
 * engine code: 9676

Porsche 997 Carrera 3.6L / 3.8L 2005 - 2008
 * engine code: 9701 / 9605

Diagram Ref No 6.

The thermostat controls coolant flow through the engine cooling circuit. When the engine is cold, restricting coolant flow through the radiators allows the engine to warm up more quickly.

Once the correct operating temperature is reached, the thermostat progressively opens to circulate coolant through the radiators and dissipate excess heat.

Correct thermostat operation helps provide:

• Stable engine temperature
• Faster warm-up from cold
• Efficient coolant circulation
• Reliable cabin-heater performance
• Improved engine efficiency
• Protection against overheating and overcooling

Symptoms of a Faulty Thermostat

• A worn or sticking thermostat can cause:
• Engine overheating
• Engine taking too long to warm up
• Fluctuating coolant temperatures
• Temperature gauge instability
• Poor cabin-heater performance
• Increased fuel consumption
• Cooling-system warning messages
• Coolant temperature remaining unusually low

A thermostat stuck closed can quickly cause overheating, while one stuck open may prevent the engine from reaching its correct operating temperature.

Recommended Cooling-System Inspection
When replacing the thermostat insert, inspect the surrounding cooling system, including:

• Thermostat housing
• Thermostat housing seal
• Water pump
• Coolant hoses
• Radiators
• Expansion tank
• Coolant level and condition
• Hose connections and clamps

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610612554

The product you are viewing cross references to these numbers

160F / 71°C Low Temperature  Water Thermostat with Insert  for 986 as well as 996 models and replaces the factory 186F thermostat insert, Porsche part numbers 996 106 125 52 (53). Also fits 987 and 997 models to 2008. Does not fit MY09+ DFI engines.

Fits:
Porsche 986 Boxster 1997 - 2004
Porsche 996 C2, C4
Porsche 987 Boxster 2005>>
Porsche 997 2005 - 2008

Installation recommended only by trained Porsche technician or Porsche service department using genuine Porsche coolant.

Diagram Ref No 5, 6

This OE Match water thermostat with insert is a replacement engine cooling system component. The low temperature 160F / 71°C specification allows the thermostat to begin opening at a lower temperature, helping coolant circulate through the radiator earlier during engine warm-up and operation.

The thermostat controls coolant flow between the engine and radiator. When the engine reaches the thermostat opening temperature, it allows coolant to circulate through the cooling system to help regulate engine operating temperature and maintain stable cooling performance.

Functions
•  Replaces the water thermostat and insert
•  Low temperature 160F / 71°C opening specification
•  Helps regulate engine coolant flow
•  Allows earlier coolant circulation through the radiator
•  Supports stable engine temperature control
•  Suitable for cooling system service or performance-focused maintenance
•  OE Match replacement for Porsche Boxster, 996, and 997 cooling systems.

Why Replace This Part?
Thermostats can fail due to age, heat cycles, coolant contamination, corrosion, internal sticking, or seal wear. A faulty thermostat may stick open or closed, causing slow warm-up, overheating, unstable temperature readings, poor heater performance, or coolant flow issues. Replacing the thermostat helps restore correct cooling system operation and temperature regulation.

When to Replace This Part
•   Engine temperature is unstable
•   The engine is overheating
•   The thermostat is stuck open or closed
•   Cooling system service is being carried out
•   Coolant is being flushed or renewed
•   Preventative cooling system maintenance is required
•   A low temperature thermostat is desired for earlier coolant circulation.

Where it fits on the car
This thermostat fits within the engine cooling system / thermostat housing area on Porsche 986 Boxster, 996, 987 Boxster, and 997 models. It controls coolant flow between the engine and radiator circuit.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610601361

The product you are viewing cross references to these numbers

160F Low Temperature Thermostat HOUSING WITH INSERT & Gasket for 986 as well as 996 models and replaces the factory 186F thermostat insert, Porsche part numbers 996 106 125 52 (53). Also fits 987 and 997 models to 2008. Does not fit MY09+ DFI engines.

Fits:
Porsche 986 Boxster 1997-2004
Porsche 996 C2, C4
Porsche 987 Boxster 2005>>
Porsche 997 2005-08

Price includes new low temperature thermostat insert manufactured in Germany by one of the same manufacturers that makes the oe thermostat insert, allowing you to reuse your original housing. Provides increased cooling capacity increasing power while ensuring consistent performance and extending engine-component longevity.

Installation recommended only by trained Porsche technician or Porsche service department using genuine Porsche coolant.

Click 'Zoom in' for large parts diagram.
Diagram Ref No 5, 6 & 7

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610601361

The product you are viewing cross references to these numbers

160F Low Temperature Thermostat housing without gasket / seal for 986 as well as 996 models and replaces the factory 186F thermostat insert, Porsche part numbers 996 106 125 52 (53). Also fits 987 and 997 models to 2008. Does not fit MY09+ DFI engines.

Fits:
Porsche 986 Boxster 1997-2004
Porsche 996 C2, C4
Porsche 987 Boxster 2005>>
Porsche 997 2005-08

Price includes new low temperature thermostat insert manufactured in Germany by one of the same manufacturers that makes the oe thermostat insert, allowing you to reuse your original housing. Provides increased cooling capacity increasing power while ensuring consistent performance and extending engine-component longevity.

Installation recommended only by trained Porsche technician or Porsche service department using genuine Porsche coolant.

Diagram Ref No 5, 6

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99610601361

The product you are viewing cross references to these numbers