2020 INFINITI QX80

Typical onset: 60,000-120,000 mi

Symptoms: Sudden loss of power with severe knocking or metallic rattling, Check engine light with multiple misfire codes and cam/crank correlation codes, Metal shavings in oil, low oil pressure warning, Engine may seize or throw connecting rod through block

Fix: The Direct Injection Timing Chain system—unique to this DI version of the VK56—can fail catastrophically when the secondary chain tensioners or guides fail, causing valve-to-piston contact and cascading internal destruction. Piston ringlands crack, bearings spin, cranks get scored. Most cases require complete short block replacement or full engine rebuild with all bearings, pistons, rings, and crank work. 25-35 labor hours for short block swap, 40-50+ for in-frame rebuild if crank needs grinding.

Estimated cost: $12,000-22,000

Symptoms: Engine stalls while driving without warning, No-start or extended cranking, especially when hot, Intermittent loss of power or hesitation, No fuel pressure at rail

Fix: The fuel pump control module fails internally, killing fuel delivery mid-drive. Covered under NHTSA recall 20V-489, but if you're out of the recall window or bought used without recall completion, expect 1.5-2 hours to replace module and clear codes. Recall work is free at dealer if VIN qualifies.

Estimated cost: $400-700

Typical onset: 70,000-110,000 mi

Symptoms: Red ATF puddles under vehicle near transmission bell housing area, Transmission overheating warnings on dash, Burnt ATF smell, Slipping or delayed shifts if fluid level drops significantly

Fix: The factory steel cooler lines corrode from road salt and moisture, especially at crimp fittings. Lines run alongside frame rails and are exposed. Requires removing skid plates and belly pans, dropping lines, replacing with OE or aftermarket steel/braided stainless. 3-4 hours labor plus fresh ATF fill and flush. Some shops replace just the leaking section, but best practice is full line set replacement to avoid repeat failures.

Estimated cost: $800-1,400

Typical onset: 80,000-130,000 mi

Symptoms: Clunking or thudding when shifting into drive or reverse, Vibration felt through floorboards at idle in gear, Excessive driveline movement visible from underneath when applying throttle in park, Transmission tail housing sags visibly on mount

Fix: The rear transmission mount deteriorates from heat and load cycles—this is a 5,500+ lb vehicle with 400 lb-ft of torque. The rubber separates from the metal core and the trans droops. Requires supporting transmission on jack, removing crossmember bolts, replacing mount. 2-2.5 hours labor. OE Nissan mount lasts longer than aftermarket rubber.

Estimated cost: $350-600

Typical onset: 50,000-90,000 mi

Symptoms: Hesitation or stumbling under acceleration, Reduced top-end power, won't pull past 4,000 RPM, Check engine light with lean fuel trim codes, Intermittent surging at highway speeds

Fix: The in-tank fuel filter can clog prematurely if the tank had sediment or if cheap fuel was used. This generation still uses an accessible cartridge filter inside the pump assembly. Requires dropping the 42-gallon fuel tank, which is a pain on the QX80's long wheelbase and frame. 3-4 hours labor including tank removal, filter replacement, and reinstallation. Always replace strainer sock at pump inlet too.

Estimated cost: $500-900

Symptoms: Random electrical gremlins: windows, mirrors, or locks intermittent, Fuel pump relay clicking repeatedly with no start, Headlights or tail lights stay on after key-off, Multiple DTCs for communication errors with body control modules

Fix: The IPDM-E is Nissan/Infiniti's central relay and fuse box in the engine bay. Internal relays (especially fuel pump relay) can fail from heat cycles and current load. Sometimes individual relays can be replaced if you can source them, but Infiniti typically wants the whole module replaced. Located driver-side engine bay. 1.5-2 hours to remove, reprogram, and reinstall. Dealer programming required for new unit.

Estimated cost: $1,200-2,000