2001 INFINITI Q45

Typical onset: 80,000-150,000 mi

Symptoms: Cold-start piston slap or knocking that persists after warm-up, Metallic rattling from cylinder bank, often worse on deceleration, Sudden loss of compression, misfire codes, eventually complete seizure, Metal shavings in oil filter, oil pressure fluctuations

Fix: This generation VK45DE has notorious weak piston skirts that crack and disintegrate. Once slap begins, it's a countdown to destruction. Requires complete engine rebuild with upgraded aftermarket pistons (Mahle or similar) or junkyard replacement. Rebuild: 18-24 hours labor plus machine shop work. Replacement: 12-16 hours swap plus uncertainty about donor condition.

Estimated cost: $4,500-8,000

Typical onset: 90,000-130,000 mi

Symptoms: Transmission fluid appears milky or strawberry-pink in dipstick, Coolant level drops without external leaks, white residue in overflow tank, Delayed engagement, slipping, or erratic shifts shortly after coolant mixing begins, Check engine light with transmission-related codes

Fix: Internal transmission cooler inside radiator develops pinhole leaks, allowing coolant and ATF to mix—destroys transmission within days if driven. Requires radiator replacement, complete transmission fluid system flush (including cooler lines, torque converter purge), and often transmission rebuild if contamination went unnoticed. Flush alone: 3-4 hours. Trans rebuild adds 10-14 hours.

Estimated cost: $800-1,200 (if caught early) or $3,500-5,500 (with trans rebuild)

Typical onset: 70,000-110,000 mi

Symptoms: Clunking over bumps from front suspension, Wandering or imprecise steering feel, especially lane changes, Uneven inner tire wear, alignment won't hold, Visible cracking or separation of rubber bushings on inspection

Fix: The large front lower control arm bushings deteriorate and tear, causing alignment shifts and poor handling. Infiniti doesn't sell bushings separately—requires complete control arm assemblies both sides. 3-4 hours labor for the pair, needs alignment after.

Estimated cost: $900-1,400

Typical onset: 100,000-150,000 mi

Symptoms: Harsh or delayed 2-3 or 3-4 upshifts, especially when cold, Transmission slips out of gear momentarily during acceleration, Check engine light with P0730, P0732, P0733 codes (gear ratio incorrect), Erratic shift points or refusal to downshift under throttle

Fix: RE5R05A transmission valve body solenoids stick or fail, causing erratic shifting. Often requires valve body removal, solenoid replacement, and fluid change. Can sometimes be improved with multiple fluid drain-and-fills using genuine Nissan Matic-J fluid. Valve body R&R: 6-8 hours.

Estimated cost: $1,200-2,200

Typical onset: 90,000-140,000 mi

Symptoms: Battery warning light intermittent or steady, Electrical system voltage drops below 13V while running, Dimming headlights, sluggish accessories, Grinding or whining noise from alternator pulley area

Fix: OE alternators fail from worn brushes or regulator. Replacement is straightforward but requires serpentine belt removal and working around tight V8 engine bay. 2-3 hours labor. Use quality rebuilt units—cheap offshore units fail quickly.

Estimated cost: $450-750

Typical onset: 80,000-120,000 mi

Symptoms: Rear sags after sitting overnight, rises after driving, Compressor runs excessively or constantly cycles, Warning message on instrument cluster about suspension, Hissing sound near air lines or struts

Fix: If equipped with air suspension, compressor seals wear and air lines crack at fittings. Compressor replacement: 2-3 hours. Air struts themselves are $$$ ($600+ each). Many owners convert to conventional coil-over struts using aftermarket kits to eliminate the complexity permanently—conversion takes 4-6 hours.

Estimated cost: $800-1,500 (compressor) or $1,200-2,000 (conversion kit installed)