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Porsche 718 Cayman Fuel Tank Cap Gaskets

Porsche 718 Cayman Fuel tank cap gaskets

Starting at low prices, AutoBuffy stocks multiple fuel tank cap gaskets from top OE-quality brands. This small rubber or cork seal sits between the fuel cap and the filler neck, keeping fuel vapors contained and moisture out. When it dries out or cracks, it triggers EVAP system faults, failed emissions tests, and fuel odor inside the cabin.

Signs your Porsche 718 Cayman needs a new fuel tank cap gasket

  • Check engine light on with an EVAP leak code (P0440, P0442, P0455, or similar)
  • Smell of raw gasoline near the rear of the vehicle, especially after filling up
  • Failed emissions or smog test due to an evaporative system leak
  • Fuel cap feels loose or does not click securely even after tightening
  • Visible cracking, flattening, or brittleness on the rubber or cork ring when you remove the cap
  • Repeated EVAP codes that return shortly after being cleared

Which fuel tank cap gasket should you buy for your Porsche 718 Cayman?

Most Porsche 718 Cayman owners need an exact-fit replacement that matches the original cap diameter and material. The key decisions are whether to replace just the gasket or the full cap assembly, and whether OEM-spec rubber or a more durable nitrile compound is the right material for your use.

Gasket-only replacement (rubber)
Best for
Budget repair when the cap body is still in good condition
What you get
Direct-fit rubber ring; lowest cost; restores the seal without replacing the whole cap
Gasket-only replacement (nitrile)
Best for
Vehicles in extreme heat climates or with ethanol-blended fuel use
What you get
Higher fuel-resistance and temperature tolerance than standard rubber; longer service life
Full cap-and-gasket assembly (aftermarket)
Best for
Cap body is cracked, ratchet is broken, or tethered cap is damaged
What you get
New cap with pre-installed gasket; eliminates fitment guesswork; often includes updated torque-limiting click mechanism
OEM-equivalent cap-and-gasket assembly
Best for
Owners who want factory specifications and part number match
What you get
Meets original manufacturer tolerances for seal compression and vapor-flow rate; highest confidence in EVAP system compliance

Replacing a fuel tank cap gasket on a Porsche 718 Cayman

Easy⏱ 15–30 minutesNo tools required for gasket-only swap in most casesSmall flathead screwdriver or pick tool (to remove old gasket from cap groove)Clean lint-free clothOBD-II scanner (to clear EVAP codes after repair)

Remove the fuel cap and pry the old gasket out of its groove using a pick or small screwdriver, being careful not to scratch the sealing surface. Press the new gasket firmly and evenly into the groove until it seats flat with no gaps or twists. Reinstall the cap, confirm it clicks, then clear any stored EVAP codes with a scan tool and drive a short cycle to allow the system to run its self-test.

Frequently asked questions

How much does it cost to replace fuel tank cap gaskets on a Porsche 718 Cayman?
A gasket-only replacement starts at low prices and is the least expensive EVAP fix available. A full cap-and-gasket assembly costs more but is still a DIY-friendly purchase. Professional installation adds minimal labor time, so total shop cost is usually just parts plus a short diagnostic fee if a scan was needed.
Will a bad fuel tank cap gasket cause a check engine light on a Porsche 718 Cayman?
Yes. A failed or cracked cap gasket allows fuel vapors to escape the EVAP system, which the Porsche 718 Cayman's onboard diagnostics detects as a small or large leak. This sets a P0440-series code and illuminates the check engine light. Replacing the gasket and clearing the code resolves the fault in most cases.
Can I drive my Porsche 718 Cayman with a leaking fuel tank cap gasket?
Short-term driving is generally safe, but it is not recommended. The open vapor leak means raw fuel vapors are escaping near the filler neck, creating a potential fire hazard and persistent fuel odor. The Porsche 718 Cayman will also continue to fail emissions tests until the gasket is replaced and the EVAP system is sealed.
How long does a fuel tank cap gasket last on a Porsche 718 Cayman?
Most cap gaskets last several years under normal conditions, but heat cycles, UV exposure, and ethanol-blended fuels accelerate hardening and cracking. Inspect the gasket any time you replace the fuel filter or notice fuel odor. If the rubber is visibly flat, cracked, or stiff, replacement is overdue regardless of mileage.
Will tightening the fuel cap fix an EVAP leak code on a Porsche 718 Cayman?
Sometimes, but only if the gasket is still pliable and the cap simply was not seated correctly. If the gasket is cracked or compressed flat, tightening will not restore an adequate seal. Remove the cap, inspect the gasket closely, and replace it if there is any visible damage before assuming the code will clear on its own.
Is a fuel tank cap gasket the same as a gas cap on a Porsche 718 Cayman?
No. The gas cap is the entire assembly you twist on and off; the gasket is only the sealing ring inside it. You can often purchase just the gasket if the cap body is intact, which costs less. If the cap body is damaged or the ratchet mechanism is worn, replacing the full cap-and-gasket assembly is the better repair.

More parts for your Porsche 718 Cayman

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Fuel tank cap gaskets for other Porsche models

Porsche 718 BoxsterPorsche BoxsterPorsche 718 SpyderPorsche CaymanPorsche 911