Coolant Bottles / Expansion Tanks

Coolant Level Sensor 99764150300 for Porsche 986 / 987 / 996 / 997

Protect your Porsche engine from potentially serious cooling system issues with this OE Match Coolant Level Sensor. Designed for Porsche 986 Boxster, 987 Boxster/Cayman, 996 and 997 models, this essential sensor continuously monitors coolant levels within the expansion tank and alerts the driver if coolant levels fall below the safe operating range.

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 996 TURBO 2000-05
• Porsche 996 GT2 2001-05
• Porsche 996 GT3 MKI 1999-02
• Porsche 996 GT3 MKII 2003>>
• Porsche 996 GT3 RS 2003-04
• 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 997 MK1 TURBO 2007-09
• Porsche 997 MK1 GT3 / GT3 RS 2007-09
• Porsche 997 MK1 GT2 2007-09
• Porsche 997 MKII Carrera C2 3.6L 2009-12
• Porsche 997 MKII Carrera C4 3.6L 2009-12
• Porsche 997 MKII Carrera C2S 3.8L 2009-12
• Porsche 997 MKII Carrera C4S 3.8L 2009-12
• Porsche 997 MKII GT3 / GT3 RS 2010-11
• Porsche 997 MKII Turbo 2010-13
• Porsche Carrera GT 2003-06

Diagram ref no 4

As a critical component of the engine cooling system, the coolant level sensor helps prevent overheating and engine damage by providing an early warning before coolant loss becomes a major problem. A faulty sensor can generate false warnings or fail to detect low coolant levels, making replacement an important part of maintaining cooling system reliability.

Manufactured to OE Match specifications, this replacement sensor offers reliable performance, precise fitment and dependable coolant level monitoring.

What Does the Coolant Level Sensor Do?

The coolant level sensor is installed within the coolant expansion tank and monitors the coolant level during vehicle operation.

Its primary functions include:

• Monitoring coolant levels
• Activating low coolant warnings
• Helping prevent engine overheating
• Protecting the engine from coolant loss
• Supporting cooling system diagnostics
• Providing driver alerts
• Improving engine reliability

By detecting coolant loss early, the sensor helps reduce the risk of costly engine damage.

Why Do Coolant Level Sensors Fail?

Coolant level sensors operate continuously in a challenging environment involving heat, pressure and coolant exposure.

Common causes of failure include:

• Age-related electronic wear
• Internal sensor deterioration
• Coolant contamination
• Corrosion of electrical contacts
• Expansion tank deterioration
• Wiring faults
• Heat cycling
• Moisture ingress

Over time, the sensor may lose accuracy or stop functioning altogether.

Symptoms of a Faulty Coolant Level Sensor

Common warning signs include:

• Coolant warning light illuminated
• Intermittent coolant level warnings
• False low coolant alerts
• Warning messages despite correct coolant level
• Cooling system fault codes
• Failure to detect genuine coolant loss
• Dashboard warning messages

In many cases, the sensor may fail before any visible cooling system issues are present.

When Should the Coolant Level Sensor Be Replaced?

Replacement is recommended when:

• False warning messages occur
• Coolant warning lights remain illuminated
• Replacing the coolant expansion tank
• Diagnosing cooling system faults
• Performing preventative maintenance
• Restoring a Porsche 986, 987, 996 or 997
• The original sensor has failed testing

Many specialists replace the sensor during coolant tank replacement as preventative maintenance.

Why Replacement Matters

A properly functioning coolant level sensor provides critical protection for your engine.

Benefits include:

• Accurate coolant level monitoring
• Early warning of coolant loss
• Reduced overheating risk
• Improved engine protection
• Enhanced cooling system reliability
• Prevention of costly repairs
• Improved driver confidence
• Long-term peace of mind

For water-cooled Porsche engines, reliable cooling system monitoring is essential

Related reference numbers
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99764150300

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Coolant Bottle / Reservoir Tank.
Comes With Black Bleeder Valve.

Fits:
Porsche 986 Boxster 1997>>2004
Porsche 987 Boxster 2005>>2006

Every car has its weak points, and although the Boxster and 996 has very few, one of the items to keep an eye on is the coolant recovery tank. Over time it becomes brittle and has a tendency to crack and leak coolant into the rear trunk area in the Boxster. A simple preventative measure is to replace your tank with a genuine Porsche recovery tank.

Diagram Ref No 7

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99610614708

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Coolant bottle / Reservoir tank, Comes with black bleeder valve.
Coolant expansion (overflow) tank for the Boxster cooling system. It serves as the reservoir for excess coolant from the radiator, allowing coolant to expand when hot and contract when cooled - keeping the system at correct pressure and preventing overflow or coolant loss.

Fits:
Porsche 986 Boxster 1997 - 2004
Porsche 987.1 Boxster 2005 - 2006

Diagram ref no 7

Replace the coolant expansion tank when you notice coolant leaks, hairline cracks, or white residue forming around the tank seams. If the tank becomes discoloured, brittle, or begins to deform from heat, it can no longer maintain proper pressure. Any signs of coolant smell in the rear trunk area, fluctuating coolant levels, or overheating symptoms also indicate the tank should be replaced.

Why replacement matters:
• Prevents coolant leaks that can cause overheating or engine damage
• Restores proper cooling-system pressure and fluid volume
• Stops air from entering the cooling system, which can lead to hot spots and poor circulation
• Prevents unexpected tank failures caused by old, brittle plastic
• Ensures clean, stable coolant flow for long-term engine reliability

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99610614708

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Coolant Bottle / Reservoir Tank.
Comes With Black Bleeder valve.

Fits:
Porsche 986 Boxster 1997>>2004
Porsche 987 Boxster 2005>>2006

Diagram Ref No 7

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99610614708

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Replacement Coolant reservoir / expansion tank cap.
This coolant expansion tank cap is a direct replacement for Porsche 996 (1998–2005) and also fits Boxster (986/987), Cayman, and 997 models, upgrading earlier versions with improved sealing and pressure control.

Fits:
Porsche 996 1998 - 2005
Porsche 997.1 2005 - 2008
Porsche 986 Boxster 1997 - 2004
Porsche 987.1 Boxster 2005 - 2008
Porsche 987C.1 Cayman 2005 - 2008

Diagram ref no 5

This cap serves as the pressure seal for the coolant expansion tank, keeping the cooling system at the correct pressure. It regulates venting to the overflow reservoir, preventing blowback, leaks, and overpressure while helping avoid coolant loss, boiling, and overheating.

It replaces earlier versions: 99610644700, 99610644701, 99610644702, 99610644703

Why replacement matters:
• An old or worn cap may fail to hold pressure, causing coolant to boil, vaporize, or overflow
• A bad cap can allow air to enter the cooling system, leading to overheating, hot spots, or poor cooling performance
• A leaking or weak cap can lead to gradual coolant loss, requiring refills and risking engine damage

Installing an OE-Match version restores proper pressure control, reliable sealing, and helps maintain engine temperature stability.


Related reference numbers
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99610644704

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Coolant Reservoir Float.

Fits:
Porsche 981 Boxster Spyder 2016>>2016
Porsche 981 Cayman 2014>>2016
Porsche 981 Cayman GT4 2016>>2016

Diagram Ref No 15

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98110615500

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Engine coolant filler neck lid
This original Porsche coolant filler lid, also known as a sealing cap or coolant bottle lid, fits the coolant filler neck and helps seal the coolant access point correctly.

Fits:
Porsche 981 Boxster 2012 - 2016
Porsche 981SP Boxster Spyder 2016
Porsche 981C Cayman 2014 - 2016
Porsche 981 Cayman GT4 2016

Porsche 982 Boxster 2017 - 2024
Porsche 982C Cayman 2017 - 2024
Porsche 982 Spyder 2019 - 2024
Porsche 982 Cayman GT4 2019 - 2024

Diagram ref no 2

This part is used in the coolant filler / water supply tank area on selected Porsche 981 and 982 Boxster / Cayman models.

What This Part Does / Functions:
•  Seals the engine coolant filler neck
•  Helps prevent coolant splash, seepage or contamination at the filler opening
•  Protects the coolant filler neck from dirt and debris
•  Supports correct cooling system service access
•  Replaces a cracked, damaged, missing or worn original lid
•  Helps maintain a clean and properly sealed coolant filler area
•  Provides correct OE Porsche fitment and finish
•  Supports correct reassembly after coolant system service.

Why Replace This Part?
The coolant filler neck lid is exposed to heat, coolant residue, repeated removal and age-related plastic wear. Over time, the lid can crack, loosen, deform, become difficult to refit or go missing during cooling system service.

Replacing it with an OE Genuine Porsche engine coolant filler neck lid helps restore the correct factory seal and appearance around the coolant filler area.

Common Symptoms of a Worn or Missing Coolant Filler
•   Lid Missing coolant filler neck lid
•   Cracked or damaged plastic cap
•   Lid no longer seats correctly
•  Coolant residue around the filler neck
•  Dirt or debris entering the coolant filler area.
•  Loose or poor-fitting coolant bottle lid
•  Damage found during coolant reservoir service
•  Incorrect non-original cap fitted.

When to Replace This Part
•   If the original lid is cracked, broken or missing
•   If the lid no longer fits securely
•   During coolant reservoir or filler neck service
•   When replacing coolant system trim or access parts
•   If the cap has become brittle from age or heat
•   After coolant maintenance if the lid is damaged
•   During engine bay / service area restoration.

Where It Fits on the Car
This lid fits on the engine coolant filler neck / coolant bottle access area. It is shown in Porsche coolant filler / water supply tank diagrams as diagram reference no. 2. Correct fitment helps keep the coolant filler area sealed, protected and finished to factory standard.

Related reference numbers
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98110604406

The product you are viewing cross references to these numbers

Engine coolant filler neck lid
OE Match engine coolant filler neck lid for Porsche 981 and 982 Boxster and Cayman, including the specified Spyder, GT4 and Clubsport applications. This replacement closes the coolant filling access point.

Fits

• Porsche 981 Boxster 2012 - 2016
• Porsche 981SP Boxster Spyder 2016
• Porsche 981C Cayman 2014 - 2016
• Porsche 981 Cayman GT4 2016
  
  
• Porsche 982 Boxster 2017 - 2024
• Porsche 982C Cayman 2017 - 2024
• Porsche 982 Spyder 2019 - 2024
• Porsche 982 Cayman GT4 2019 - 2024
  
  

Diagram ref no 2


What This Product Does

The lid forms the closure at the coolant filling neck, covering the opening between servicing operations. It helps exclude debris and keeps the access area properly closed after coolant maintenance.

Functions

• Closes the coolant filling opening.
• Shields the access point against dirt.
• Restores the closure when the previous lid is damaged or absent.
• Allows the filling area to be closed again following service work.

Technical Details

• Brand: OE Match.
• Supplied part reference: 98110604406.
• Identified in the supplied diagrams as a coolant end cap or water closure cap.
• Located within the coolant reservoir and filling-neck assembly.

Symptoms of Fault

• Visible cracks, distortion or broken sections.
• A closure that sits loosely or cannot be refitted correctly.
• An uncovered filling opening following loss of the lid.
• Residue or debris around the access point requiring inspection.
• Brittleness or damage discovered during reservoir maintenance.

Why Replacement Matters

Repeated handling, ageing and exposure to heat can leave the closure damaged or poorly seated. Renewing an unsuitable lid restores the intended closure of the filling access point. OE Match develops replacement components around Porsche applications, using original references and fitment checks to guide specification.

Inspect the adjoining neck before installation. Coolant loss or temperature warnings require diagnosis of the cooling system rather than assuming this access lid is responsible.

Reference Numbers

98110604406; 98110604405; 98110604404; 98110604403. Compare the vehicle's original reference and application details when selecting a replacement.

FAQs

Is it the expansion-tank pressure cap?
No. The supplied assembly diagrams distinguish this filling-neck closure from the separate reservoir pressure cap.

When should the lid be renewed?
Replace it if damaged, absent, distorted or unable to seat securely. Check the neck for related damage at the same time.

Related reference numbers
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98110604406

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Expansion Tank Cover.

Fits:
Porsche 986 Boxster 1997>>2004
Porsche 987 Boxster 2005>>2008

Diagram Ref No 13

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99610623401

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Expansion Tank Cover.

Fits:
Porsche 986 Boxster 1997-05
Porsche 987 Boxster 2005-06

Click 'Zoom in' for large parts diagram.
Diagram ref no 14.

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98650464400

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Expansion tank. Porsche 987 Boxster / 987 Cayman

Fits:
Porsche 987 Boxster 2.7L Boxster S 3.4L 2007-08 Chassisc no F988U7 02382>> and F988U7 22205>>
Porsche 987 Boxster 2.9L / Boxster S 3.4L 2009-12
Porsche 987C Cayman 2.7L / Cayman S 3.4L 2006-08 Chassis no F988U7 52756>> and F988U7 72799>>
Porsche 987C Cayman 2.9L / Cayman S 3.4L 2009-12

Click 'Zoom in' for large parts diagram.
Diagram ref no 1

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98710604703

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Expansion tank.

Fits:
Porsche 987 Boxster 2.7L Boxster S 3.4L 2007-08 Chassis no F988U7 02382>> and F988U7 22205>>
Porsche 987 Boxster 2.9L / Boxster S 3.4L 2009-12
Porsche 987C Cayman 2.7L / Cayman S 3.4L 2006-08 Chassis no F988U7 52756>> and F988U7 72799>>
Porsche 987C Cayman 2.9L / Cayman S 3.4L 2009-12

Click 'Zoom in' for large parts diagram.
Diagram ref no 1

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98710604703

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Filler neck to washer tank gasket

Fits:
Porsche 991.1 Carrera 2012-16
Porsche 991.2 Carrera / Turbo / GT3 2017>>
Porsche 981 Boxster / S / Spyder 2012-16
Porsche 982 (718) Boxster 2017>>
Porsche 981C Cayman / S / GT4 2012-16
Porsche 981C (718) Cayman 2017>>
Porsche 955 Cayenne 2003-06
Porsche 957 Cayenne 2007-10
Porsche 958 Cayenne 2011-18

Click 'Zoom in' for large parts diagram.
Diagram ref no 2

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Lid for maintenance cup. Satin Black. Porsche 987 Boxster / 987C Cayman

Fits:
Porsche 987 Boxster 2005-08
Porsche 987C Cayman 2005-08

Click 'Zoom in' for large parts diagram.
Diagram ref no 18

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9875513720101C

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Fits:
Porsche 987 Boxster 2005-08
Porsche 987C Cayman 2005-08

Porsche 987 Gen 2 Boxster 2009-12
Porsche 987C Gen 2 Cayman 2009-12

Click 'Zoom in' for large parts diagram.
Diagram ref no 2

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Oil And Coolant Caps With Seals Included.

Fits:
Porsche 987.1 Boxster MKI 2005>>2008
Porsche 987.2 Boxster MKII 2009>>2012
Porsche 987.1 Cayman MKI 2005>>2008
Porsche 987.2 Cayman MKII 2009>>2012

Diagram Ref No 1 (Diagram Ref No 3, 4, 5 And 6 Included)

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