Fuel Cap

Replacement of the fuel cap on a 2009 Aston Martin DB9, including inspection of the tether and filler neck seal.

Warnings

Tools required

Parts

• Fuel cap × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and turn off engine
2. Allow fuel system to depressurize naturally (no action required for fuel cap replacement)
3. Ensure fuel filler door release is functioning properly

Procedure

1. 1

   Open fuel filler door
   Release the fuel filler door; on the DB9 the filler flap is typically released in conjunction with the central locking system (unlocking the vehicle), and there may not be a separate dedicated interior switch. Verify the exact release method against the vehicle owner's manual. The door will release slightly; open it fully to access the fuel cap. Note: On the DB9 the filler door is typically released via the central locking system rather than a mechanical floor lever; verify exact method against the owner's manual.he door will open to access the fuel cap. Note: Release the fuel filler door using the interior fuel filler release control (verify exact location and type against the owner's manual, typically a button/switch rather than a floor lever). The door will release slightly; open it fully to access the fuel cap.
2. 2

   Remove existing fuel cap
   Rotate the fuel cap counterclockwise until it releases from the filler neck. The cap may be tethered to the filler door assembly; verify against OEM documentation whether a tether is present and its attachment method before proceeding. Allow any residual fuel vapors to dissipate. Allow any residual fuel vapors to dissipate before proceeding. Note: The cap may be tethered to the filler assembly; if a tether is present, it will remain attached via the retaining strap. Verify the actual attachment point against OEM documentation. Note: The cap may be tethered to the filler assembly via a plastic or metal tether strap; verify the actual retention method on this vehicle before proceeding.
3. 3

   Inspect tether attachment point
   Examine the tether connection point on both the cap and the filler door mounting bracket. If the tether is damaged or the cap needs replacement including the tether assembly, note the attachment method. The tether typically clips or snaps into a bracket molded into the filler door housing.
4. 4

   Remove tether if replacing cap assembly
   If replacing the entire cap assembly with tether, disconnect the tether from the filler door bracket by pressing the release tab or pulling the tether connector straight out from its mounting point. If only replacing the cap and reusing the tether, skip this step.
5. 5

   Inspect filler neck seal
   Use an inspection light to examine the rubber seal inside the fuel filler neck. Look for cracks, deformation, or fuel staining that would indicate seal degradation. Clean any debris from the sealing surface using a clean, lint-free cloth.
6. 6

   Install new fuel cap tether
   If installing a new cap with tether, connect the tether to the filler door bracket by inserting the tether connector into the mounting point until it clicks or seats fully. Verify the tether has adequate slack to allow the cap to thread fully onto the filler neck without strain.
7. 7

   Install new fuel cap
   Align the new fuel cap threads with the filler neck threads. Rotate the cap clockwise until it seats against the filler neck seal. Continue rotating until the cap seats and, if it has a ratcheting mechanism, until it clicks indicating proper engagement and sealing (verify the correct number of clicks against OEM specification). Do not over-tighten. Note: Continue rotating until it clicks, indicating proper engagement and sealing (refer to OEM specification for the correct number of clicks). Do not over-tighten beyond the clicking point. Note: Continue rotating until the cap engages and clicks per the OEM cap design (verify the correct number of clicks for this cap). Do not over-tighten beyond the engagement point.
8. 8

   Verify cap installation
   Attempt to rotate the cap counterclockwise slightly; it should resist movement if properly seated. Check that the tether is not kinked or under excessive tension. Close the fuel filler door and verify it latches securely.

Reassembly

1. No disassembly was required; installation is complete after fuel cap is properly threaded and sealed

Verification

• Close fuel filler door fully and ensure it latches without obstruction from the cap or tether
• Start vehicle and verify no check engine light or fuel system warnings appear on instrument cluster
• After driving, check for fuel odor around the filler door area; absence of odor confirms proper seal

More procedures for this vehicle