Knock Sensor

This procedure covers removal and replacement of the knock sensor(s) on the 2009 Aston Martin DB9 6.0L V12 engine, requiring intake manifold removal for access.

Warnings

Tools required

Parts

• Knock sensor (bank 1) × 1 — Use OEM specification
• Knock sensor (bank 2) × 1 — Use OEM specification
• Intake manifold gasket set × 1 — Use OEM specification
• Coolant hose clamps (if damaged) × 2 — Use OEM specification

Fluids

• coolant — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Disconnect battery negative terminal and wait 10 minutes
4. Relieve fuel system pressure by removing fuel pump fuse and attempting to start engine until it fails to run
5. Place drain container under radiator drain and partially drain coolant to below intake manifold level (approximately 2 quarts)
6. Remove engine cover by releasing mounting points
7. Photograph all electrical connectors and hose routing before disassembly

Procedure

1. 1

   Remove Air Intake System
   Disconnect mass airflow sensor electrical connector. Loosen clamps securing air intake tubes to throttle bodies. Remove air filter housing by releasing mounting fasteners (typically Torx). Disconnect any breather hoses from valve covers. Remove complete intake tubing assembly from both banks to provide access to intake manifold.
2. 2

   Disconnect Fuel System Components
   Disconnect fuel rail electrical connectors for injectors on both banks. Release fuel line quick-connect fittings at fuel rails using appropriate tool. Cover open fuel lines with shop towels to prevent contamination. Disconnect fuel pressure sensor connector if equipped.
3. 3

   Disconnect Throttle Bodies and Ancillary Components
   Disconnect throttle body electrical connectors on both banks. Remove throttle body coolant hoses by releasing clamps (mark orientation). Disconnect any vacuum lines connected to intake manifold, marking each for reinstallation. Disconnect brake booster vacuum line. Remove any engine wiring harness brackets mounted to intake manifold.
4. 4

   Remove Intake Manifold Fasteners
   Locate and remove all intake manifold mounting bolts. The DB9 V12 intake manifold is secured with multiple fasteners around the perimeter. Work systematically from outside to inside, loosening bolts in reverse of tightening sequence (typically from center outward). Remove all fasteners completely and store organized by location. Note: Intake manifold bolt count and torque sequence unverified — confirm exact fastener count and factory tightening sequence against Aston Martin service documentation
5. 5

   Remove Intake Manifold Assembly
   Carefully lift intake manifold assembly straight up and away from engine. The manifold is large and awkward on the V12; use care to avoid damaging sensors or wiring. Set manifold on clean work surface with gasket side up. Inspect gasket surfaces on cylinder heads for damage or debris.
6. 6

   Locate Knock Sensors
   With intake manifold removed, locate knock sensors on both banks of the engine block. The knock sensors are mounted on the engine block; verify exact quantity and location against Aston Martin service documentation for the 6.0L V12, as sensor count and mounting position (valley vs. outer block faces per bank) must be confirmed before proceeding. Clean the area around sensors with brake cleaner and shop towels. Note: With intake manifold removed, locate the knock sensors on the engine block. The exact mounting location and quantity of knock sensors on the DB9 6.0L V12 must be confirmed against OEM documentation (they may be mounted on the sides of the block beneath the exhaust manifolds rather than in the valley, and there may be more than two). Clean the area around the sensors before removal. Note: With access gained, locate the knock sensors on the engine block. Consult OEM documentation for the exact number and position of knock sensors on the 2009 Aston Martin DB9 6.0L V12, as location and quantity must be verified against factory service data before proceeding. Clean the area around each sensor with brake cleaner and shop towels. Note: Knock sensor count and location unverified — V12 engines commonly use four sensors (two per bank); verify against Aston Martin service documentation before ordering parts
7. 7

   Disconnect Knock Sensor Electrical Connectors
   Carefully disconnect electrical connectors from both knock sensors. Note connector orientation and any locking tabs. Inspect connectors for corrosion or damage. Trace wiring harness to any mounting clips and release harness from block to provide slack.
8. 8

   Remove Knock Sensors
   Using the appropriate tool, carefully remove both knock sensors by turning counterclockwise. Confirm the fastener type and socket size against OEM documentation, as the sensors may use a hex-head retaining bolt rather than a threaded body. If sensors are seized, apply penetrating oil and allow to soak before removal. Do not use excessive force as threads in aluminum block can be damaged. Remove sensors completely and inspect threads in block. Note: Using the correct socket size specified in Aston Martin service documentation, carefully remove both knock sensors by turning counterclockwise. Note: Using the appropriate socket (verify size against OEM documentation), carefully remove each knock sensor by turning counterclockwise. Note that some sensors on this engine family are bolt-retained rather than threaded. Note: socket size unverified — confirm against Aston Martin service documentation (sensor may be bolt-retained rather than threaded-body)
9. 9

   Prepare Block and New Sensors
   Clean knock sensor mounting holes in block using wire brush and brake cleaner. Ensure threads are clean and free of debris or old anti-seize. Inspect new knock sensors to confirm correct part numbers match original sensors. Install the knock sensors DRY unless OEM documentation specifically calls for a thread treatment. Do not apply anti-seize or lubricant to the threads, body, or tip, as this can alter clamp load and corrupt knock signal transmission. Note: Install knock sensors dry — do NOT apply anti-seize, thread locker, or any lubricant to the sensor or threads. Anti-seize alters the torque-to-clamp-load relationship and can degrade the sensor's vibration coupling to the block, causing false or missed knock detection. Ensure mounting surface is clean.
10. 10

    Install New Knock Sensors
    Thread new knock sensors into block by hand until fully seated against mounting surface. Ensure sensors thread smoothly without cross-threading. Using a torque wrench and appropriate socket, tighten the knock sensors to the OEM-specified torque value (verify against factory documentation before applying). This torque is critical for proper sensor operation and signal quality. Do not over-tighten. Note: Using torque wrench and appropriate socket, tighten knock sensors to the Aston Martin factory-specified torque value (confirm exact figure in OEM documentation before final tightening). Note: Using a torque wrench and appropriate socket, tighten each knock sensor to the OEM specification (verify exact value against factory service data before final tightening). This torque is critical for proper sensor operation and signal quality. Do not over-tighten.
    Torque spec

    Knock Sensor20 Nm (15 lb-ft)
11. 11

    Reconnect Knock Sensor Electrical Connectors
    Connect electrical connectors to both knock sensors, ensuring they click securely into place. Verify connector locks are engaged. Route wiring harness back through mounting clips to prevent interference with moving components. Verify harness has adequate slack and is not under tension.
12. 12

    Prepare for Intake Manifold Installation
    Clean intake manifold mating surfaces on both cylinder heads using plastic scraper and brake cleaner. Remove all old gasket material without scratching aluminum surfaces. Ensure surfaces are completely clean and dry. Position new intake manifold gaskets on cylinder heads, aligning all ports and bolt holes. Some gaskets may have alignment pins or adhesive backing.
13. 13

    Install Intake Manifold
    Carefully lower intake manifold assembly onto cylinder heads, aligning with gaskets and all mounting holes. Ensure no wiring or hoses are pinched beneath manifold. Install all manifold mounting bolts finger-tight. Tighten the intake manifold bolts to the OEM-specified torque value following the exact factory tightening sequence and staging (verify sequence and torque against factory documentation). Follow OEM torque specification for intake manifold bolts. Note: Intake manifold torque value and tightening sequence unverified — obtain exact torque spec and staging pattern from Aston Martin factory service documentation
14. 14

    Reconnect All Components to Intake Manifold
    Reconnect throttle body coolant hoses with new clamps if originals are damaged. Connect all vacuum lines to proper ports using reference photos. Reconnect brake booster vacuum line. Install any engine wiring harness brackets removed earlier. Connect throttle body electrical connectors on both banks.
15. 15

    Reconnect Fuel System and Air Intake
    Reconnect fuel lines to fuel rails, ensuring quick-connect fittings are fully seated. Reconnect all fuel injector electrical connectors. Reconnect fuel pressure sensor if equipped. Install complete air intake system in reverse of removal, ensuring mass airflow sensor is properly connected and all clamps are tight. Reconnect any breather hoses to valve covers.
16. 16

    Refill Coolant and Reconnect Battery
    Refill the cooling system with the OEM-specified coolant mixed 50/50 to the proper level (confirm coolant type and approximate refill quantity against factory documentation). Reconnect battery negative terminal. Install engine cover. Start engine and allow to reach operating temperature while monitoring for coolant leaks. Check coolant level and top off as needed after bleeding air from system. Note: Refill cooling system with the Aston Martin-specified coolant mixed 50/50 to proper level (verify exact coolant specification and quantity lost against OEM documentation). Note: Refill the cooling system with the OEM-specified coolant (verify chemistry and type against Aston Martin service data) at the correct mix ratio to proper level, replacing the volume lost during the procedure. Bleed air from the system per factory procedure.

Reassembly

1. Reinstall components in reverse order of removal
2. Ensure all electrical connectors are fully seated and locked
3. Verify all vacuum lines and coolant hoses are properly routed and secured
4. Double-check torque on knock sensors before manifold installation
5. Follow proper torque sequence for intake manifold bolts per OEM specification

Verification

• Start engine and verify smooth idle with no misfires or rough running
• Use OBD-II scan tool to verify no knock sensor fault codes are present
• Monitor live data for knock sensor signal response (should show activity during light acceleration)
• Check for coolant leaks around intake manifold and coolant hoses
• Check for vacuum leaks by listening for hissing sounds around intake manifold
• Verify fuel system has no leaks at rail connections
• Test drive vehicle and verify normal engine performance with no knock detection under load

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