The Q45 is Infiniti's flagship V8 sedan with solid engineering but plagued by expensive transmission failures, engine piston/ring issues in certain years, and aging electrical gremlins. Parts availability is declining and repair costs can exceed vehicle value quickly.
RE4R01A/RE5R05A Automatic Transmission Failure
Common · high severityTypical onset: 90,000-140,000 mi
Symptoms: Harsh or delayed 2-3 shift, especially when cold, Slipping in 3rd or 4th gear under load, Whining or grinding noise from bell housing area, Transmission overheating, burnt fluid smell
Fix: Transmission rebuild or replacement required. Oil cooler lines often corrode internally and send debris into valve body. Expect 12-16 hours labor for R&R and rebuild. Remanufactured units are getting scarce for earlier models.
Estimated cost: $3,200-5,500
VH45DE Piston Ring Land Failure and Bore Scoring
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: Excessive oil consumption, 1+ quart per 1,000 miles, Blue smoke on startup or acceleration, Loss of compression in one or more cylinders, Rough idle, misfires that don't resolve with ignition work
Fix: Piston ring lands crack due to carbon buildup and detonation. Requires full teardown, bore measurement, honing or sleeving, new pistons and rings. 35-45 hours labor for in-frame rebuild. Some owners opt for used engine swap instead.
Estimated cost: $5,500-8,500
Alternator Failure and Battery Drain Issues
Common · medium severityTypical onset: 80,000-120,000 mi
Symptoms: Battery dies after sitting 2-3 days, Dimming headlights at idle, Charging voltage below 13.5V or fluctuating, Electrical accessories acting erratically
Fix: Factory Mitsubishi alternators fail internally, often the regulator or diode pack. Also common: parasitic draw from trunk-mounted amp or radio module staying awake. Alternator replacement is 2-3 hours. Tracking parasitic draw adds 1-2 hours diagnostic time.
Estimated cost: $450-850
Front and Rear Suspension Bushing Deterioration
Common · medium severityTypical onset: 100,000-150,000 mi
Symptoms: Clunking over bumps, especially front lower control arms, Wandering steering, requires constant correction, Uneven tire wear on inside edges, Rear end feels loose or unstable in corners
Fix: Multi-link suspension uses numerous rubber bushings that rot out. Front lower control arm bushings and rear subframe bushings are worst. Alignment mandatory after replacement. Budget 6-8 hours for full front and rear refresh.
Estimated cost: $1,200-2,000
HVAC Blend Door Actuator and Heater Core Failure
Occasional · low severityTypical onset: 90,000-140,000 mi
Symptoms: Clicking or ticking noise from dash when adjusting temperature, Heat or A/C stuck on one side only, Sweet coolant smell in cabin, Foggy windshield that won't clear, wet passenger floor
Fix: Blend door actuators fail and jam. Heater core leaks require full dash removal. Actuator alone is 2-3 hours. Heater core replacement is 10-14 hours due to dash disassembly and A/C system recovery/recharge.
Estimated cost: $600-2,800
Active Suspension (HICAS/Sonar) System Failures
Occasional · medium severityTypical onset: 70,000-110,000 mi
Symptoms: HICAS or Active Suspension warning light on dash, Hydraulic pump whining under hood, Suspension rides extremely harsh or too soft, Fluid leaks from hydraulic lines or accumulator
Fix: Later models with active suspension have complex hydraulic systems that fail. Accumulators, pump, and solenoids all age out. Many owners convert to passive shocks/springs. Fixing properly requires dealer-level diagnostics and scarce parts, 6-10 hours labor.
Estimated cost: $1,800-4,000
Timing Chain Tensioner and Guide Rail Wear
Occasional · high severityTypical onset: 150,000+ mi
Symptoms: Rattling noise from front of engine on cold start, quiets after 5-10 seconds, Metal shavings in oil filter media, Check engine light with cam/crank correlation codes, Engine runs rough or won't start if chain jumps
Fix: VH45DE uses timing chains with plastic guides that wear. If chain jumps time, valve-to-piston contact can occur. Replacement requires removing front covers, water pump, and timing components. 12-16 hours labor, preventive job at 150k recommended.
Estimated cost: $1,800-3,200
Buy only if you're handy or have a trusted independent Nissan specialist—these are money pits for the average owner, but rewarding if you can wrench and find clean examples under 100k miles.
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.