The 2005 DB9's 6.0L V12 is a hand-built marvel that suffers from catastrophic engine failures due to main bearing weaknesses, along with transmission cooler leaks and aging electrical gremlins. Beautiful when running, but engine rebuilds are nearly inevitable and ruinously expensive.
Main Bearing Failure (Catastrophic Engine Damage)
Common · high severityTypical onset: 40,000-80,000 mi
Symptoms: Metallic knocking from lower engine, especially on cold start, Rapid oil pressure drop or fluctuating oil pressure gauge, Metal shavings in oil filter during changes, Sudden catastrophic failure with complete engine seizure
Fix: Engine-out complete teardown and rebuild. Main bearings themselves are a design flaw — inadequate oil supply to journals 4 and 5 causes bearing wear and subsequent crankshaft damage. Requires 60-80 labor hours for engine removal, machine work, replacement of crank (often), all bearings, seals, gaskets, timing components, and reinstallation. Some shops do upgraded bearing kits with improved oil delivery. This is THE killer issue on these cars.
Estimated cost: $18,000-30,000
Transmission Oil Cooler Leaks
Common · medium severityTypical onset: 50,000-90,000 mi
Symptoms: Transmission fluid leaking from front of engine bay, Pink or red fluid pooling under car after sitting, Low transmission fluid warnings on dash, Delayed or harsh shifting when fluid level drops
Fix: The ZF 6-speed auto's external cooler and lines corrode and develop leaks. Cooler is mounted low and exposed to road debris. Replacement involves dropping undertray, draining trans, replacing cooler assembly and often hoses. 4-6 labor hours plus fluid refill and system bleeding.
Estimated cost: $1,200-2,200
Transmission Mounts Deterioration
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking when shifting from Park to Drive or Reverse, Vibration through chassis at idle or under acceleration, Visible transmission sag when inspected on lift, Excessive driveline movement during throttle changes
Fix: Hydraulic transmission mounts fail from age and heat cycles. Trans must be supported while mounts are replaced. Access is tight in the DB9's rear-mid layout. 5-7 labor hours for both mounts, plus alignment check afterward.
Estimated cost: $1,500-2,500
Fuel System Contamination and Filter Clogging
Occasional · medium severityTypical onset: Any mileage after sitting or using ethanol fuels
Symptoms: Rough idle, misfires, or stumbling acceleration, Fuel pump whine or surging sounds from rear, Check engine light with lean codes (P0171/P0174), Sudden loss of power or stalling
Fix: Ethanol fuel degrades rubber hoses and sends debris into the tank. Main fuel filter clogs; pump pre-filters also affected. If car sat for extended periods, tank may need dropping and cleaning. Filter replacement alone is 2-3 hours (in-tank access requires dropping tank or rear subframe). Full tank cleaning and pump replacement: 8-12 hours.
Estimated cost: $800-1,500 (filter), $3,000-5,000 (full tank service)
Battery Cable Corrosion and Electrical Faults
Common · low severityTypical onset: Any age, worsens after 10+ years
Symptoms: Intermittent no-start or clicking when key turned, Random warning lights on dash (ABS, airbag, transmission), Accessories cutting out or flickering, Parasitic drain causing dead battery after sitting
Fix: Battery is trunk-mounted; positive cable runs full length of car and corrodes at junction points. NHTSA recall addressed some cables but corrosion continues. Replacement of main cables: 3-5 hours. Diagnosis of electrical gremlins can add significant time. Use dielectric grease on all connections during service.
Estimated cost: $600-1,200
Head Gasket Seepage (Not Full Failure)
Occasional · low severityTypical onset: 70,000-120,000 mi
Symptoms: Minor oil weeping from valve cover or head gasket area, Slight coolant smell from engine bay after hard driving, Slow coolant loss without visible external leaks, Oil residue on spark plug threads
Fix: The V12's aluminum heads expand/contract differently than the block. Gaskets seep more than blow catastrophically. If caught early, some owners defer repair until engine-out work is needed for other reasons (like bearings). Head gasket replacement alone: 25-35 hours labor due to V12 complexity and tight engine bay. Often done alongside main bearing rebuild to avoid redundant labor.
Estimated cost: $8,000-12,000 (standalone), often bundled with bearing rebuild
Only buy if you have a $25,000 engine-rebuild fund set aside or can verify recent professional engine overhaul with upgraded bearings — otherwise you're buying a ticking time bomb, no matter how pampered the service history looks.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.