Transmission Range Sensor

Replace the transmission range sensor (neutral safety switch) on a 2009 Aston Martin DB9 with 6.0L V12 and Touchtronic 6-speed automatic transmission.

Warnings

Tools required

Parts

• Transmission range sensor × 1 — Use OEM specification
• Transmission range sensor O-ring or gasket × 1 — Usually included with sensor

Fluids

• transmission_auto — 2.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake.
2. Disconnect negative battery cable and wait 5 minutes for system capacitors to discharge.
3. Raise vehicle on lift or securely support on jack stands at manufacturer-recommended lift points.
4. Remove undertray panels to access transmission from below using Torx fasteners.
5. Locate transmission range sensor on driver's side of transmission case, near shift linkage connection.
6. Clean area around sensor thoroughly to prevent contamination from entering transmission during removal.
7. Position drain pan directly beneath sensor location to catch fluid spillage.

Procedure

1. 1

   Disconnect sensor electrical connector
   Locate the electrical connector on the transmission range sensor. Press the locking tab and carefully pull the connector straight off the sensor. Inspect connector terminals and pins for corrosion or damage. If using a multimeter, note resistance values across sensor terminals for comparison with new sensor (optional diagnostic step).
2. 2

   Remove sensor retaining hardware
   The transmission range sensor retaining hardware configuration must be confirmed against OEM documentation; it may be secured by fasteners and/or a retaining clip on the selector shaft. Remove the retaining fastener(s) completely using the appropriate driver (verify exact count and drive type against OEM documentation). Keep fasteners organized for reinstallation. Note the sensor's rotational orientation relative to the transmission case before removal. Note: The transmission range sensor is secured by fastener(s) — verify exact count and drive type against DB9 service documentation before removal.
3. 3

   Extract transmission range sensor
   Carefully pull the sensor straight out from the transmission case. Be prepared for some transmission fluid seepage from the sensor bore; position a drain pan to catch any fluid. Verify whether significant fluid loss occurs for this application before assuming a full refill is required. Remove the old O-ring or gasket from the sensor bore in the transmission case using a pick or small flat-blade screwdriver. Thoroughly clean the sealing surface, removing all old gasket material and debris. Note: Carefully pull the sensor straight out from the transmission case. Be prepared for some transmission fluid to seep from the sensor bore; position a drain pan beneath. Verify actual fluid loss against factory documentation, as this sensor may release only a small amount of fluid rather than draining the transmission.
4. 4

   Prepare new transmission range sensor
   Unpack the new transmission range sensor and verify it matches the original design. Install the new O-ring or gasket onto the sensor body, ensuring it seats properly in the groove. Lightly lubricate the O-ring with clean ATF to ease installation and prevent damage during insertion. Inspect the sensor shaft and ensure it moves freely through its range of motion.
5. 5

   Install new sensor
   Align the sensor shaft with the detent in the transmission case (the shaft has a specific keyed orientation). Insert the sensor straight into the bore, ensuring the O-ring does not roll or pinch. Rotate the sensor body to align the mounting holes with the transmission case holes. The sensor should sit flush against the transmission case surface.
6. 6

   Secure sensor with fasteners
   Install the range sensor retaining fastener(s) finger-tight first to ensure proper thread engagement (verify exact fastener count and drive type against DB9/ZF service documentation). Tighten the fastener(s) to the manufacturer-specified torque, using a crossing pattern if more than one fastener is present (verify exact value and count against OEM/ZF service documentation before final tightening). Do not overtighten, as this may crack the sensor body or strip aluminum threads in the transmission case. Note: Tighten the fasteners in a crossing pattern to the factory-specified torque (verify exact value against DB9 service documentation before final tightening).
7. 7

   Reconnect electrical connector
   Push the electrical connector firmly onto the sensor until the locking tab clicks into place. Verify the connection is secure by gently tugging on the connector. Ensure the wiring harness is properly routed and not in contact with hot exhaust components or sharp edges.
8. 8

   Refill transmission fluid
   Locate the transmission fill plug on the side of the transmission case (may require removing additional underbody panels depending on access). Using a fluid transfer pump and flexible extension, refill the transmission with the manufacturer-approved ATF for the ZF 6HP26 (verify exact fluid specification — commonly ZF Lifeguard 6 / Shell M-1375.4 — against Aston Martin service documentation before use) through the fill port, replacing only the quantity lost during service (verify exact capacity against OEM documentation). Fluid should be at operating temperature (35-45°C / 95-113°F) for proper level verification. Fill until fluid begins to weep from the fill plug hole with engine running and transmission in Park. Note: refill the transmission with ZF-approved ATF (ZF Lifeguard 6 / Shell M-1375.4 specification) through the fill port, adding a volume equal to the amount drained (typically approximately 1 quart) and then setting the final level by the fill-plug method Note: Locate the transmission fill plug on the side of the transmission case (may require removing additional underbody panels depending on access). Using a fluid transfer pump and flexible extension, refill the transmission with ZF-approved ATF (ZF Lifeguard 6 / Shell M-1375.4 specification) through the fill port, adding only the volume lost during sensor service (verify exact amount against factory documentation). Note: Using a fluid transfer pump and flexible extension, refill the transmission with the ZF-approved ATF specified for the 6HP26 (e.g., ZF Lifeguard 6 or OEM-approved equivalent). Add fluid to replace only the amount lost during sensor removal; verify exact refill quantity against factory documentation before proceeding.
9. 9

   Verify fluid level and check for leaks
   With vehicle still raised and level, start the engine and allow it to reach operating temperature. Cycle the transmission through all gear positions (P-R-N-D and manual mode positions) while depressing the brake pedal, pausing 3-5 seconds in each position. Return to Park. Check fluid level at the fill plug with engine running; fluid should barely drip from fill hole at correct level. Top off if necessary, then reinstall fill plug. Inspect the new sensor installation area for any signs of fluid leakage.
10. 10

    Reinstall undertray and lower vehicle
    Reinstall all undertray panels removed during preparation, ensuring all Torx fasteners are properly seated. Lower vehicle to ground. Reconnect negative battery cable.
11. 11

    Clear fault codes and perform relearn procedure
    Using an appropriate diagnostic scanner, clear any stored transmission-related fault codes. If required, perform any transmission range sensor adaptation or calibration using the manufacturer-specified diagnostic procedure and equipment. Verify the correct relearn steps against OEM service documentation. Start engine and verify that gear position display on instrument cluster matches actual selector position in all gears. Note: move gear selector slowly through all available positions (P-R-N-D and manual/Sport mode), pausing 5 seconds in each position

Reassembly

1. Reinstallation follows the reverse order of removal, with particular attention to sensor shaft alignment and O-ring installation.
2. Ensure all undertray panels are securely fastened and properly aligned.
3. Perform complete transmission function test including all gear positions before returning vehicle to service.

Verification

• Start engine and verify that instrument cluster correctly displays each gear position as selector is moved through P-R-N-D-S.
• Verify engine only starts in Park and Neutral positions (neutral safety function).
• Verify reverse lights illuminate when transmission is in Reverse.
• Test drive vehicle and confirm smooth shifting through all gears with no transmission fault warnings.
• Recheck transmission fluid level after test drive and top off if necessary.
• Inspect sensor area one final time for any fluid leakage after test drive.

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