Flex Pipe

Replace the exhaust flex pipe (flexible coupling) on the exhaust system, which allows for engine movement and absorbs vibration between rigid exhaust sections.

Warnings

Tools required

Parts

• Exhaust flex pipe assembly × 1 — Use OEM Aston Martin specification
• Exhaust flange gaskets × 2 — Use OEM specification
• Oxygen sensor (if damaged during removal) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and allow exhaust system to cool completely (minimum 2 hours)
2. Disconnect negative battery terminal to prevent accidental airbag deployment or electrical issues
3. Raise vehicle on lift or secure on jack stands at all four corners, ensuring adequate working clearance underneath
4. Apply penetrating oil liberally to all exhaust clamp fasteners, flange bolts, and oxygen sensor threads in the work area
5. Inspect the flex pipe location and identify all connecting components, hangers, and sensors in the immediate area
6. Protect surrounding components with heat-resistant shields if using torch for fastener removal

Procedure

1. 1

   Remove oxygen sensor from affected section
   Locate the oxygen sensor(s) in the exhaust section containing the flex pipe (typically downstream of catalytic converters). Disconnect the wiring harness connector by releasing the locking tab. Using an oxygen sensor socket (verify the exact size against Aston Martin service data for this vehicle), carefully unthread the sensor from the exhaust pipe. If sensor is seized, apply heat carefully to the bung (not the sensor) and retry. Inspect sensor condition; replace if damaged or threads contaminated. Note: Using an oxygen sensor socket (commonly 22mm, verify fitment for this sensor), carefully unthread the sensor from the exhaust pipe. Note: Using an oxygen sensor socket (commonly 22mm / 7/8", verify fitment for this application), carefully unthread the sensor from the exhaust pipe.
   Torque spec

   O2 Sensor45 Nm (33 lb-ft)
2. 2

   Remove upstream exhaust clamp or flange connection
   Identify the connection method upstream of the flex pipe. If clamped, remove the band clamp fasteners (verify exact count and head type against OEM documentation before purchasing tools). If flanged, remove the flange bolts securing the connection. Count and document all fasteners removed. Support the exhaust section with a jack or hanger to prevent excessive movement. Note: If clamped, remove the band clamp fasteners (verify exact fastener type and count against Aston Martin service data for this vehicle before beginning). Note: If clamped, remove the band clamp fasteners. If flanged, remove the flange bolts securing the connection. Verify the exact fastener type and count against OEM documentation for this specific vehicle before beginning. Note: Fastener count and type unverified — confirm against Aston Martin service documentation for the 2009 DB9 6.0L V12 before proceeding
3. 3

   Remove downstream exhaust clamp or flange connection
   Locate the connection point downstream of the flex pipe. Remove the band clamp fasteners or flange bolts as applicable. Verify the specific connection method and fastener head type at the flex pipe joints against OEM documentation for this vehicle. Keep fasteners organized by location for reassembly. Note: Verify the exact connection type and fastener style (band clamp, flange bolts, Torx/E-Torx/hex) against Aston Martin service documentation for this vehicle before removal. Note: Verify the connection method at the flex pipe against OEM documentation; it may be a band clamp or bolted flange depending on exhaust configuration.
4. 4

   Disconnect exhaust hangers
   Identify all rubber exhaust hangers supporting the section containing the flex pipe (confirm exact hanger count and locations against Aston Martin service data for this vehicle). Using an exhaust hanger tool or pry bar, carefully work each hanger stud out of its rubber isolator. Apply lubricant to ease removal. Support the exhaust section weight to prevent strain on remaining connections. Note: Identify all rubber exhaust hangers supporting the section containing the flex pipe (confirm exact hanger count and locations on the vehicle). Note: Identify all rubber exhaust hangers supporting the section containing the flex pipe. Confirm the exact hanger count and locations for this specific vehicle before removal. Note: Hanger count unverified — confirm exact number and locations against Aston Martin service documentation for this vehicle
   ⚠Exhaust hangers store tension. Control the exhaust section as hangers are released to prevent sudden dropping or swinging.
5. 5

   Remove flex pipe section from vehicle
   With all connections and hangers released, carefully maneuver the exhaust section containing the flex pipe out from under the vehicle. The section may need to be rotated or angled to clear suspension components, driveshaft, and chassis members. Note the routing path for reinstallation. Place removed section on a clean work surface.
6. 6

   Remove flex pipe from exhaust section (if not replacing entire section)
   If replacing only the flex pipe and not the entire exhaust section, identify the fasteners or clamps securing the flex pipe to adjacent pipes. Remove these fasteners (typically band clamps with Torx fasteners). Cut and remove old gaskets. If the flex pipe is welded in place, this procedure requires cutting and welding, which significantly changes the repair approach.
7. 7

   Clean all mating surfaces and inspect connections
   Using a wire brush and gasket scraper, thoroughly clean all exhaust flange mating surfaces, clamp seating areas, and oxygen sensor bungs. Remove all carbon deposits, old gasket material, and corrosion. Inspect flanges for warping or cracks. Check oxygen sensor bung threads for damage. Verify new flex pipe fitment against old component.
8. 8

   Install new flex pipe into exhaust section
   If replacing flex pipe within the section, position the new flex pipe with proper orientation (flex bellows should allow for engine movement axis). Install new band clamps or flange connections finger-tight. Ensure proper alignment before tightening. If installing a complete new section, proceed to step 9.
9. 9

   Position exhaust section under vehicle
   Carefully maneuver the exhaust section (with new flex pipe) back into position under the vehicle, following the noted routing path. Align hanger studs with rubber isolators but do not fully seat yet. Support the section with a jack or assistant to maintain approximate alignment with mating flanges or clamp positions.
10. 10

    Install new gaskets and connect upstream joint
    Place new exhaust gaskets on the upstream flange or sealing surface. Align the joint and install fasteners finger-tight. For flanged connections, use a cross-pattern tightening sequence. Do not torque to specification yet; leave connections loose enough to allow alignment adjustment.
11. 11

    Connect downstream joint
    Install new gaskets at the downstream connection point. Align the joint and install clamp or flange fasteners finger-tight. Verify that the flex pipe is positioned with adequate clearance from surrounding components (minimum 25mm clearance from driveshaft, suspension, and chassis) and that no binding or excessive stretching exists.
12. 12

    Install exhaust hangers
    With joints loosely connected, work each rubber hanger isolator onto its corresponding exhaust hanger stud. Apply lubricant to ease installation. Ensure all hangers are fully seated and that exhaust system sits in natural position without forced alignment. The system should have slight movement capability at hangers.
    Torque spec

    Hanger Bolts27 Nm (20 lb-ft)
13. 13

    Torque all exhaust connections
    Beginning with the upstream connection, torque all exhaust clamp bolts or flange fasteners to specification in a cross-pattern sequence. Move to the downstream connection and repeat. Verify all connections are secure and gaskets are properly seated. Double-check clearances after torquing, as components may shift slightly.
    Torque spec

    Exhaust Clamps55 Nm (41 lb-ft)
14. 14

    Reinstall oxygen sensor
    Apply a thin coat of anti-seize compound to the oxygen sensor threads (avoid contaminating the sensor tip). Thread the sensor into the bung by hand until seated, then torque to specification using the oxygen sensor socket. Reconnect the wiring harness connector and ensure the locking tab engages fully. Route wiring away from hot exhaust components and secure with existing clips.
    ⚠Apply anti-seize only to threads, never to sensor tip. Contamination will cause sensor failure and check engine light.
    Torque spec

    O2 Sensor45 Nm (33 lb-ft)
15. 15

    Final inspection and clearance verification
    Perform a complete visual inspection of the installation. Verify all fasteners are torqued, all hangers are seated, oxygen sensor is connected, and no tools or parts remain in the work area. Check clearances at all points around the flex pipe section, ensuring minimum 25mm clearance from all surrounding components. Verify the flex pipe bellows can move freely without binding.

Reassembly

1. Reconnect negative battery terminal
2. Lower vehicle from lift or jack stands
3. Start engine and allow to idle, listening for exhaust leaks at all connection points
4. If leaks are detected, allow system to cool and re-torque affected connections
5. Clear any diagnostic trouble codes related to oxygen sensors using appropriate scan tool

Verification

• With engine running, inspect all exhaust connections for leaks (visible exhaust smoke or audible hissing)
• Rev engine to 2500-3000 RPM and verify no leaks develop under increased exhaust flow
• Verify no contact between exhaust components and vehicle chassis, suspension, or driveshaft throughout engine RPM range
• Road test vehicle and verify no exhaust rattles, buzzes, or abnormal sounds during acceleration and deceleration
• Check for check engine light; scan for oxygen sensor codes (P0130-P0141 range) and verify no new faults present
• Perform final visual inspection after test drive to confirm all connections remain secure and no new leaks have developed

More procedures for this vehicle