The 2005 Q45 is Infiniti's flagship sedan with a 4.5L VK45DE V8 making 340hp, known for luxury and performance but plagued by catastrophic engine failures and transmission cooling issues that can total the car if not caught early.
VK45DE Engine Bore Scoring and Piston Ring Failure
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: Excessive oil consumption (quart every 500-1000 miles), Blue smoke on cold start or acceleration, Rough idle and misfires on multiple cylinders, Loss of compression and power, Metallic rattling from cylinder walls
Fix: This is the Q45's Achilles heel. Cylinder walls score due to inadequate oiling during cold starts and aggressive driving. Requires complete engine rebuild with cylinder bore reconditioning, new pistons/rings, bearings, and head work. 35-45 hours labor. Many owners opt for low-mileage JDM replacement engines (15-20 hours swap) instead of rebuild due to cost.
Estimated cost: $6,500-12,000
Transmission Oil Cooler Line Failure and Cross-Contamination
Common · high severityTypical onset: 90,000-150,000 mi
Symptoms: Pink or milky coolant in overflow tank, Transmission fluid looks like strawberry milkshake, Harsh shifting or slipping, Overheating transmission or engine, Coolant loss with no external leaks
Fix: The transmission oil cooler inside the radiator fails, allowing ATF and coolant to mix. This destroys the transmission rapidly. Requires radiator replacement, transmission flush (or rebuild if contamination went too far), all cooler lines, and coolant system flush. If caught immediately, 8-12 hours. If transmission damaged, add 18-25 hours for rebuild.
Estimated cost: $1,800-6,500
Transmission Mount Collapse
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Severe clunk when shifting from Park to Drive or Reverse, Vibration at idle in gear, Driveline shudder during acceleration, Visible transmission sag when inspected on lift
Fix: The rear transmission mount hydraulic fluid leaks out and the mount collapses. Replacement is straightforward but requires supporting the transmission. 2.5-3.5 hours labor. Replace both front and rear mounts as a pair for longevity.
Estimated cost: $450-750
Timing Chain Tensioner and Guide Wear
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: Rattling from front of engine on cold start (first 5-10 seconds), Check engine light with timing correlation codes, Rough running or misfires, Metal shavings in oil filter
Fix: VK45 uses timing chains with hydraulic tensioners that wear or fail. Secondary chain guides crack. If chains skip teeth, valve damage occurs. Requires front engine disassembly, all three chains, tensioners, guides, and new VVT gears recommended. 18-24 hours labor. Do water pump, valve cover gaskets, and front main seal while in there.
Estimated cost: $3,200-4,800
VVEL System Actuator Failure (Variable Valve Event & Lift)
Occasional · medium severityTypical onset: 100,000-160,000 mi
Symptoms: Check engine light with P1084 or P1087 codes, Reduced power and poor throttle response, Rough idle and stumbling, VVEL actuator whining noise from valve covers
Fix: The VVEL actuator motors on each cylinder head fail from internal wear. Requires valve cover removal and actuator replacement (dealer-only part, expensive). 4-6 hours per bank. Some shops attempt actuator motor rebuilds for half the cost but reliability varies.
Estimated cost: $2,000-3,500
Front Lower Control Arm Bushings and Ball Joints
Common · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking over bumps from front end, Wandering steering or poor alignment retention, Uneven tire wear on inside edges, Steering wheel vibration at highway speeds
Fix: Front lower control arms use press-in bushings that crack and ball joints that develop play. Infiniti sells complete arms only (no bushings separately). Replace both sides with alignment. 4-5 hours labor for both sides.
Estimated cost: $900-1,400
Brake Light Switch Failure (NHTSA Recall Addressed but Repeat Failures)
Occasional · medium severitySymptoms: Brake lights stay on continuously, Brake lights don't illuminate when pedal pressed, Cannot shift out of Park, Cruise control won't engage, Battery drain if lights stuck on
Fix: Original recall replaced switches but replacements still fail. Switch is behind brake pedal. Simple replacement but must ensure proper adjustment for shift interlock function. 0.5-1.0 hours labor.
Estimated cost: $150-280
Only buy if under 80k miles with impeccable service records and budget for a potential engine replacement—this is a spectacular car when healthy but catastrophically expensive when the VK45 grenades.
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.