DIY Diagnostic Guide: Mastering Every Generation of Infiniti FX35 Failures

When Infiniti launched the FX35, it flipped the premium SUV segment completely on its head. Melding a muscular, bionic-cheetah design aesthetic with the legendary Nissan FM (Front Midship) sports car architecture, the FX35 drove more like a lifted sports sedan than a lumbering family hauler.

At the absolute heart of its widespread appeal was the iconic VQ series three-point-five-liter V6 engine—a high-revving, distinctively sounding powerplant that delivered genuine enthusiast credentials. Coupled with an available rear-biased intelligent all-wheel-drive platform, the FX35 was engineered to dominate asphalt rather than dirt trails.

However, cramming high-performance sports car DNA into a heavy sport-utility chassis meant that certain mechanical assemblies took an absolute beating. Furthermore, Infiniti's early push into cutting-edge cabin tech and high-end interior treatments introduced specific design eccentricities that age far less gracefully than the underlying steel.

For the dedicated DIYer, keeping an FX35 tracking straight and sounding sweet requires a sharp diagnostic mind to isolate engineered design shortcomings from the typical wear-and-tear of automotive old age.

The First Generation (S50: 2003–2008) & Facelift (2006)

The original S50 FX35 debuted with a stiff, athletic suspension tune, short overhangs, and the naturally aspirated VQ35DE V6 engine routing power through a five-speed automatic transmission. The mid-cycle 2006 refresh brought minor cosmetic updates to the grille, standard leather seating, a revised center console, and a tech package featuring an early iteration of lane departure warning.

Component Failure Breakdown

• Powertrain & Variable Valve Timing Control
  • Design Imperfections (Inherent): Weak internal paper gaskets behind the timing chain cover that blow out and bleed off oil pressure to the variable valve timing (VVT) actuators; failure-prone valve cover oil gallery tubes that are molded directly into the plastic cover assembly, causing spark plug wells to flood with engine oil.
  • Age & Mileage Wear (Natural): Leaking oil cooler O-ring seals located right at the oil filter housing base; drying out of the rear differential fluid bushing causing structural fluid leaks.
• Electrical, Cabin Tech & Body Geometry
  • Design Imperfections (Inherent): Severe bubbling and blistering of the upper dashboard skin material when exposed to UV heat (famously nicknamed the "dashboard measles"); internal plastic gear stripping within the power window motor regulator track assemblies.
  • Age & Mileage Wear (Natural): Snapping rear hatch latch release cables; corrosion on the exhaust system mid-pipe flange junctions.

The Five-Sense DIY Diagnostic Toolkit

👂 Hear

• A metallic slapping, rattling, or clicking sound from the front of the engine during a warm idle indicates that the internal paper timing cover gaskets have blown out, starving the timing chain tensioners of hydraulic oil pressure and letting the main chain whip against its plastic guides.
• A loud, rhythmic grinding or binding noise from the door panels when you press the power window button tells you the soft internal plastic driver gears inside the window motor have completely stripped out.

👀 See

• Thick pools of fresh engine oil filling up the depths of the spark plug wells when you pull the ignition coils confirms that the integrated spark plug tube seals have failed. Because the seals are molded into the plastic cover, you must replace the entire valve cover assembly.
• The check engine light casting a steady glow with codes P0011 or P0021 stored on your code scanner reveals that the VVT cams are not reaching their targeted advance timing parameters due to internal oil pressure bleed-off.

👃 Smell

• A pungent, bitter scent of burning oil wafting through the front radiator grille or entering the climate control system after high-RPM driving points directly to a hardened oil cooler ring seal weeping oil onto the hot exhaust Y-pipe beneath.

✋ Touch

• A rough, bumpy, and blistered texture across the top surface of the passenger-side dashboard area confirms the infamous UV-induced chemical breakdown of the factory dashboard foam bonding agent.
• A sharp, clunking sensation felt right through the floorboards when shifting the transmission from reverse into drive indicates that the liquid-filled rear differential bushing has torn open and lost its dampening fluid.

🛠️ Tech Diagnostics (OBD-II & Pressure Testing)

• The Warm Engine Oil Pressure Test: If you suspect blown internal timing cover gaskets, connect a mechanical oil pressure gauge to the engine block switch port. Warm the engine fully up to operating temperature. If your oil pressure drops significantly below the factory minimum specification at idle (fourteen PSI) despite a healthy oil pump, oil is escaping past the blown internal paper gaskets.
• The Multimeter Window Switch Check: If a window refuses to budge, pull the master switch panel and back-probe the harness pins with a digital multimeter. If you read a solid twelve volts traveling to the motor when pressing the toggle switch, but the glass remains locked in place, the electrical circuitry is intact and the mechanical window motor regulator gear is stripped.

The Second Generation (S51: 2009–2013)

The second-generation FX35 arrived with a highly aggressive front snout, functional side vents to relieve under-hood air pressure, and a revised double-wishbone front suspension architecture. The powertrain transitioned to the updated VQ35HR engine—boasting dual throttle bodies, an elevated redline, and a symmetrical twin-intake layout—harnessed to a crisp seven-speed automatic transmission.

Component Failure Breakdown

• Engine Management, Intakes & Cooling
  • Design Imperfections (Inherent): Accelerated internal degradation of the plastic steering wheel clock-spring ribbon cable, leading to random failure of steering wheel audio controls and cruise buttons; fragile plastic steering lock module assemblies that fail to unlock the steering wheel column, stranding the car in a total "no-crank" state.
  • Age & Mileage Wear (Natural): Hairline cracking across the plastic top tank of the radiator assembly; carbon crusting over the dual electronic throttle body butterfly plates causing erratic idle targets.
• Chassis, Hub Assembly & Brakes
  • Design Imperfections (Inherent): Premature wear of the front wheel bearing hub assemblies due to the vehicle's aggressive factory negative camber configuration and stiff lateral suspension loading.
  • Age & Mileage Wear (Natural): Tearing of the rubber compliance bushings on the aluminum front lower control arms; dry-rotting rubber brake caliper slide pin boots.

The Five-Sense DIY Diagnostic Toolkit

👂 Hear

• A low-pitched, drone, hum, or helicopter-like whirring noise from the front end that grows progressively louder as vehicle speed climbs—and intensifies sharply when you lean the vehicle's weight into a turn—signals a failing front wheel bearing hub assembly.
• A complete, dead silence from the starter motor when you push the dashboard ignition button, with zero cranking noises but a faint clicking sound beneath the steering column, indicates the electronic steering lock actuator is mechanically jammed.

👀 See

• An erratic, hunting engine idle speed that bounces up and down between six hundred and one thousand RPM on your tachometer dial indicates that heavy carbon deposits have accumulated along the edges of the dual throttle body plates, throwing off the mass airflow sensor algorithms.
• A steady, weeping stream of bright green or blue fluid staining the bottom engine splash shield reveals that the plastic upper radiator tank has developed a heat-fatigue hairline split along its crimp seam.

👃 Smell

• The chemical odor of boiling, sweet engine coolant radiating from the front fender wells after a highway commute indicates that cooling system pressure is pushing vapor through a hairline radiator fracture.

✋ Touch

• A distinct, loose pulling or tracking sensation through the steering wheel when braking lightly over uneven asphalt roads indicates that the inner rubber compliance bushings of the lower control arms have shifted or torn apart.

🛠️ Tech Diagnostics (OBD-II & Specialized Scanners)

• The Steering Lock Bypass Test: When confronted with a "no-crank, no-start" scenario where the dashboard ignition switch remains completely locked out, connect an advanced bi-directional OBD-II scan tool to the diagnostic port. Check the Body Control Module (BCM) for steering lock communication faults. To diagnose a mechanical jam on the fly, tap the underside of the steering lock module casing with a rubber mallet while cycling the push-start button to see if the internal locking pin frees itself.
• The Hub Runout and Dial Indicator Test: To definitively pinpoint which front wheel bearing is failing before it develops obvious physical slack, jack up the front axle and secure it safely on stands. Secure a dial indicator gauge to the steering knuckle body and place the measuring tip against the brake rotor face. Rotate the hub by hand; if your total runout reading exceeds factory tolerance limits, or if you feel a distinct grittiness through the spring coil when spinning the wheel, that hub assembly must be swapped.

Summarized DIY Preventative Inspection Routine

Keep this quick-reference matrix handy for your routine garage checks or when inspecting a pre-owned FX35 for purchase:

⚠️ Critical Safety Note on All-Wheel-Drive (AWD) Diagnostics: The Infiniti FX35 utilizes an advanced, electronically controlled ATTESA E-TS all-wheel-drive system that proactively vectors torque to the front wheels via an electromagnetic clutch pack inside the transfer case. If you are lifting the vehicle to troubleshoot drivetrain noises, wheel bearings, or axle binding, never run the engine with the vehicle shifted into gear while only one axle or one side of the vehicle is supported by jack stands. The vehicle's computer module will instantly detect the speed differential between the spinning wheels and the stationary wheels, locking up the internal transfer case clutch pack to divert power. This can violently launch the SUV off the jack stands within a fraction of a second. Always support the chassis uniformly on four certified, heavy-duty jack stands placed under the factory frame lifting hooks before engaging the drivetrain for diagnosis.

DIY Diagnostic Guide: Mastering Every Generation of Infiniti FX35 Failures

When Infiniti launched the FX35, it flipped the premium SUV segment completely on its head. Melding a muscular, bionic-cheetah design aesthetic with the legendary Nissan FM (Front Midship) sports car architecture, the FX35 drove more like a lifted sports sedan than a lumbering family hauler.

At the absolute heart of its widespread appeal was the iconic VQ series three-point-five-liter V6 engine—a high-revving, distinctively sounding powerplant that delivered genuine enthusiast credentials. Coupled with an available rear-biased intelligent all-wheel-drive platform, the FX35 was engineered to dominate asphalt rather than dirt trails.

However, cramming high-performance sports car DNA into a heavy sport-utility chassis meant that certain mechanical assemblies took an absolute beating. Furthermore, Infiniti's early push into cutting-edge cabin tech and high-end interior treatments introduced specific design eccentricities that age far less gracefully than the underlying steel.

For the dedicated DIYer, keeping an FX35 tracking straight and sounding sweet requires a sharp diagnostic mind to isolate engineered design shortcomings from the typical wear-and-tear of automotive old age.

The First Generation (S50: 2003–2008) & Facelift (2006)

The original S50 FX35 debuted with a stiff, athletic suspension tune, short overhangs, and the naturally aspirated VQ35DE V6 engine routing power through a five-speed automatic transmission. The mid-cycle 2006 refresh brought minor cosmetic updates to the grille, standard leather seating, a revised center console, and a tech package featuring an early iteration of lane departure warning.

Component Failure Breakdown

• Powertrain & Variable Valve Timing Control
  • Design Imperfections (Inherent): Weak internal paper gaskets behind the timing chain cover that blow out and bleed off oil pressure to the variable valve timing (VVT) actuators; failure-prone valve cover oil gallery tubes that are molded directly into the plastic cover assembly, causing spark plug wells to flood with engine oil.
  • Age & Mileage Wear (Natural): Leaking oil cooler O-ring seals located right at the oil filter housing base; drying out of the rear differential fluid bushing causing structural fluid leaks.
• Electrical, Cabin Tech & Body Geometry
  • Design Imperfections (Inherent): Severe bubbling and blistering of the upper dashboard skin material when exposed to UV heat (famously nicknamed the "dashboard measles"); internal plastic gear stripping within the power window motor regulator track assemblies.
  • Age & Mileage Wear (Natural): Snapping rear hatch latch release cables; corrosion on the exhaust system mid-pipe flange junctions.

The Five-Sense DIY Diagnostic Toolkit

👂 Hear

• A metallic slapping, rattling, or clicking sound from the front of the engine during a warm idle indicates that the internal paper timing cover gaskets have blown out, starving the timing chain tensioners of hydraulic oil pressure and letting the main chain whip against its plastic guides.
• A loud, rhythmic grinding or binding noise from the door panels when you press the power window button tells you the soft internal plastic driver gears inside the window motor have completely stripped out.

👀 See

• Thick pools of fresh engine oil filling up the depths of the spark plug wells when you pull the ignition coils confirms that the integrated spark plug tube seals have failed. Because the seals are molded into the plastic cover, you must replace the entire valve cover assembly.
• The check engine light casting a steady glow with codes P0011 or P0021 stored on your code scanner reveals that the VVT cams are not reaching their targeted advance timing parameters due to internal oil pressure bleed-off.

👃 Smell

• A pungent, bitter scent of burning oil wafting through the front radiator grille or entering the climate control system after high-RPM driving points directly to a hardened oil cooler ring seal weeping oil onto the hot exhaust Y-pipe beneath.

✋ Touch

• A rough, bumpy, and blistered texture across the top surface of the passenger-side dashboard area confirms the infamous UV-induced chemical breakdown of the factory dashboard foam bonding agent.
• A sharp, clunking sensation felt right through the floorboards when shifting the transmission from reverse into drive indicates that the liquid-filled rear differential bushing has torn open and lost its dampening fluid.

🛠️ Tech Diagnostics (OBD-II & Pressure Testing)

• The Warm Engine Oil Pressure Test: If you suspect blown internal timing cover gaskets, connect a mechanical oil pressure gauge to the engine block switch port. Warm the engine fully up to operating temperature. If your oil pressure drops significantly below the factory minimum specification at idle (fourteen PSI) despite a healthy oil pump, oil is escaping past the blown internal paper gaskets.
• The Multimeter Window Switch Check: If a window refuses to budge, pull the master switch panel and back-probe the harness pins with a digital multimeter. If you read a solid twelve volts traveling to the motor when pressing the toggle switch, but the glass remains locked in place, the electrical circuitry is intact and the mechanical window motor regulator gear is stripped.

The Second Generation (S51: 2009–2013)

The second-generation FX35 arrived with a highly aggressive front snout, functional side vents to relieve under-hood air pressure, and a revised double-wishbone front suspension architecture. The powertrain transitioned to the updated VQ35HR engine—boasting dual throttle bodies, an elevated redline, and a symmetrical twin-intake layout—harnessed to a crisp seven-speed automatic transmission.

Component Failure Breakdown

• Engine Management, Intakes & Cooling
  • Design Imperfections (Inherent): Accelerated internal degradation of the plastic steering wheel clock-spring ribbon cable, leading to random failure of steering wheel audio controls and cruise buttons; fragile plastic steering lock module assemblies that fail to unlock the steering wheel column, stranding the car in a total "no-crank" state.
  • Age & Mileage Wear (Natural): Hairline cracking across the plastic top tank of the radiator assembly; carbon crusting over the dual electronic throttle body butterfly plates causing erratic idle targets.
• Chassis, Hub Assembly & Brakes
  • Design Imperfections (Inherent): Premature wear of the front wheel bearing hub assemblies due to the vehicle's aggressive factory negative camber configuration and stiff lateral suspension loading.
  • Age & Mileage Wear (Natural): Tearing of the rubber compliance bushings on the aluminum front lower control arms; dry-rotting rubber brake caliper slide pin boots.

The Five-Sense DIY Diagnostic Toolkit

👂 Hear

• A low-pitched, drone, hum, or helicopter-like whirring noise from the front end that grows progressively louder as vehicle speed climbs—and intensifies sharply when you lean the vehicle's weight into a turn—signals a failing front wheel bearing hub assembly.
• A complete, dead silence from the starter motor when you push the dashboard ignition button, with zero cranking noises but a faint clicking sound beneath the steering column, indicates the electronic steering lock actuator is mechanically jammed.

👀 See

• An erratic, hunting engine idle speed that bounces up and down between six hundred and one thousand RPM on your tachometer dial indicates that heavy carbon deposits have accumulated along the edges of the dual throttle body plates, throwing off the mass airflow sensor algorithms.
• A steady, weeping stream of bright green or blue fluid staining the bottom engine splash shield reveals that the plastic upper radiator tank has developed a heat-fatigue hairline split along its crimp seam.

👃 Smell

• The chemical odor of boiling, sweet engine coolant radiating from the front fender wells after a highway commute indicates that cooling system pressure is pushing vapor through a hairline radiator fracture.

✋ Touch

• A distinct, loose pulling or tracking sensation through the steering wheel when braking lightly over uneven asphalt roads indicates that the inner rubber compliance bushings of the lower control arms have shifted or torn apart.

🛠️ Tech Diagnostics (OBD-II & Specialized Scanners)

• The Steering Lock Bypass Test: When confronted with a "no-crank, no-start" scenario where the dashboard ignition switch remains completely locked out, connect an advanced bi-directional OBD-II scan tool to the diagnostic port. Check the Body Control Module (BCM) for steering lock communication faults. To diagnose a mechanical jam on the fly, tap the underside of the steering lock module casing with a rubber mallet while cycling the push-start button to see if the internal locking pin frees itself.
• The Hub Runout and Dial Indicator Test: To definitively pinpoint which front wheel bearing is failing before it develops obvious physical slack, jack up the front axle and secure it safely on stands. Secure a dial indicator gauge to the steering knuckle body and place the measuring tip against the brake rotor face. Rotate the hub by hand; if your total runout reading exceeds factory tolerance limits, or if you feel a distinct grittiness through the spring coil when spinning the wheel, that hub assembly must be swapped.

Summarized DIY Preventative Inspection Routine

Keep this quick-reference matrix handy for your routine garage checks or when inspecting a pre-owned FX35 for purchase:

⚠️ Critical Safety Note on All-Wheel-Drive (AWD) Diagnostics: The Infiniti FX35 utilizes an advanced, electronically controlled ATTESA E-TS all-wheel-drive system that proactively vectors torque to the front wheels via an electromagnetic clutch pack inside the transfer case. If you are lifting the vehicle to troubleshoot drivetrain noises, wheel bearings, or axle binding, never run the engine with the vehicle shifted into gear while only one axle or one side of the vehicle is supported by jack stands. The vehicle's computer module will instantly detect the speed differential between the spinning wheels and the stationary wheels, locking up the internal transfer case clutch pack to divert power. This can violently launch the SUV off the jack stands within a fraction of a second. Always support the chassis uniformly on four certified, heavy-duty jack stands placed under the factory frame lifting hooks before engaging the drivetrain for diagnosis.