Infiniti Q50 3.7
3.7L V6 with VVEL variable valve lift — 330 hp at 7,000 rpm, 7,500 rpm redline, that cultured VQ sound. Oil gallery gaskets behind the timing chain cover are the critical weak point: when they fail, oil pressure drops with no external leak visible. Pre-purchase inspection: always check for P0011/P0021 codes. ESCL steering lock issues on early 2009–2012 builds.
Q50 3.7 — the underrated V6 before the twin-turbo arrived
330 hp from the 3.7 VVEL — naturally aspirated, high-revving, better soundtrack than the twin-turbo. No boost lag, no turbo seal concerns. Oil gallery gaskets are the key check at purchase. The 3.7 Q50 from 2014-2015 is a undervalued sport sedan. DAS failure can happen — verify steering at all temperatures.
Engine Weaknesses 12
Paper-based oil gallery gaskets behind the front timing chain cover swell or tear. Oil pressure drops with no external leak visible — camshafts and bearings become oil-starved. Nissan later switched to improved metal gaskets.
Symptoms: Low oil pressure when warm (below 30 psi at idle), P0011/P0021 fault codes, jerky acceleration
At high mileage and with spirited use, connecting rod and main bearing wear can occur. The engine does not tolerate running with a low oil level, which can result from the sealing issues.
Symptoms: Metallic knocking on load changes, oil pressure warning, rough engine running at high revs
The internal concentric slave cylinder (CSC) of the FS6R31A gearbox is a known design defect. The thin aluminium housing is attacked by brake fluid and develops cracks — often under 50,000 km. Subject of a US class action lawsuit.
Symptoms: Clutch pedal drops to the floor without warning, car cannot be put into gear, clutch fluid dripping from gearbox
The rear driveshaft retaining nut can work loose through vibration. In extreme cases the wheel hub detaches and the wheel falls off. Nissan issued a recall for 2013–2015 models.
Symptoms: Vibration or clonking from the rear axle area, increasing noise in corners, in extreme cases sudden loss of control
If a VVEL actuator is removed individually, it must be recalibrated to exactly 5.5° inclination. Without Consult-III software the engine enters limp mode or will not start at all. Nissan list price per actuator: approx. €3,500–4,000.
Symptoms: After engine work: P1090 (right bank) or P1092 (left bank), engine runs on three cylinders, will not rev above 3,500 rpm, limp mode.
Defective valve stem seals on older VQ37VHR engines allow oil into the combustion chamber. Consumption clearly exceeds Nissan's guideline of 1 qt/10,000 miles.
Symptoms: Blue smoke on cold start, oil consumption above 1 qt/10,000 miles, oil on spark plug electrodes
Crankshaft sensor fails from around 100,000 miles. Engine dies suddenly while driving. OEM sensors only — aftermarket parts fail more frequently.
Symptoms: Engine dies while driving, P0335, intermittent starting problems, unable to restart
VQ37VHR can produce a brief timing chain rattle on cold start that disappears after 2–5 seconds. Worn chain tensioners need time to build oil pressure. If neglected the chain can jump.
Symptoms: Metallic rattle for 2–5 seconds immediately after cold start, disappears once oil pressure builds
OEM catalytic converters can become blocked by oil residue on vehicles with elevated oil consumption. Fault codes P0420/P0430 appear and power drops.
Symptoms: Power loss in upper rev range, MIL with P0420/P0430, sluggish throttle response
The FS6R31A 6-speed manual gearbox shows synchro ring wear in 2nd and 3rd gear under spirited driving. Pre-2013 early models also suffered cold-weather shift problems. High-quality gearbox oil delays the issue.
Symptoms: Crunching or grating when selecting 2nd and 3rd gear, especially with a cold gearbox or fast gear changes
VQ37VHR valve cover gaskets become leaky with mileage and cause oil loss. Oil reaches spark plugs and can cause misfires. Simple, inexpensive repair.
Symptoms: Oily smell in engine bay, visible oil traces, oil on spark plugs, occasional misfires
VQ37VHR camshaft sensor wears from around 85,000 miles (fault code P0345). Stop-and-go driving accelerates wear through heat exposure.
Symptoms: Check engine light P0345, slight stuttering, rough idle
Vehicle Weaknesses 8
The steer-by-wire DAS system loses power assist in cold temperatures or with transient voltage drops. Steering wheel becomes extremely heavy or momentarily locks. Three redundant ECUs but no redundant sensors — all three modules must be replaced as a set. Repair costs $3,000–7,000. NHTSA recall 16V-430 issued 2016.
Active Lane Control (ALC) system triggers Chassis Control warnings or applies incorrect steering corrections — pulling toward exits or oncoming lane. Wheel speed sensor faults are common cause.
Sunroof drain tubes clog with debris and overflow into the cabin. Water pools on driver-side floor and can damage electrical components. TSB issued in 2015. Drain valve 74816-JU40B has a known design flaw guaranteeing leakage.
Brake rotors develop thickness variation from 30,000 miles through brake pad compound deposits. TSB ITB15-018 identifies undersized brake pin on Sport versions with 4-piston calipers. Repair cost approximately $500.
InTouch dual-screen system freezes or shows black screen while driving. Early 2014 models worst affected due to slower processor. InTouch finished last in satisfaction rankings with only 38% of owners very satisfied.
Door lock actuators fail on driver and passenger doors. Door does not lock or unlock via key fob, interior button, or handle. Control chip failure linked to temperature cycling. Repair around $600.
Window regulator motors and cable guides fail from around 50,000 miles. Window gets stuck mid-travel or fails to close fully. Driver window more frequently affected. Replacement costs $350–$950.
Steering wheel leather coating peels and flakes, especially around control button areas. More pronounced on dark interiors. Infiniti does not offer free replacement outside warranty. DIY PlastiDip refinish is a common workaround.
