The 2004 Altima is split between a reliable 2.5L four-cylinder and a problematic 3.5L V6 that suffers catastrophic pre-cat failure, plus CVT transmission issues that plague both engines. The QR25DE is solid; the VQ35DE is a ticking time bomb.
Pre-Catalytic Converter Failure Leading to Engine Destruction (3.5L V6 Only)
Common · high severityTypical onset: 70,000-120,000 mi
Symptoms: Rattling from engine bay on cold start that disappears when warm, Loss of power and rough idle, Check engine light with multiple misfire codes (P0300-P0306), Metallic debris in oil during changes, Catastrophic engine failure if driven after symptoms appear
Fix: The pre-cats inside the exhaust manifolds disintegrate and get sucked back into cylinders, scoring cylinder walls and destroying pistons/rings. Requires complete engine rebuild or replacement. Preventive fix is replacing factory manifolds with aftermarket units before failure (8-10 hours labor). Post-failure needs full rebuild with bore/hone or short block swap (25-35 hours).
Estimated cost: $4,500-8,500
CVT Transmission Failure (RE4F04B)
Common · high severityTypical onset: 80,000-130,000 mi
Symptoms: Whining or grinding noise during acceleration, Shuddering between 15-30 mph, Hesitation or slipping when accelerating from stop, Transmission overheating warning light, Sudden loss of forward gears
Fix: These early CVTs have weak valve bodies and fail bearings. Transmission cooler lines also leak into radiator causing cross-contamination (the 'strawberry milkshake of death'). Flush and external cooler addition extends life but most need full replacement or rebuild. R&R is 8-10 hours; rebuilt units run $2,500-3,200 plus installation.
Estimated cost: $3,200-4,800
Crankshaft Position Sensor Failure
Common · medium severityTypical onset: 60,000-110,000 mi
Symptoms: No-start condition with cranking but no fire, Intermittent stalling while driving, especially when hot, Check engine light with P0335 or P0340 codes, Engine cuts out then restarts after cooling
Fix: Sensor mounted on bellhousing fails from heat cycling. Common failure point that leaves you stranded but easy fix. Replace sensor and connector pigtail if corroded (1.5-2 hours labor). Always replace when doing transmission work as access is same.
Estimated cost: $180-320
Front Lower Control Arm Bushing Deterioration
Common · low severityTypical onset: 70,000-100,000 mi
Symptoms: Clunking over bumps from front end, Steering wheel off-center after hitting potholes, Uneven tire wear on inside edges, Wandering or loose steering feel
Fix: Front LCA bushings crack and separate, most common on driver side. Cannot press new bushings into old arms on this chassis—must replace complete control arms. Both sides plus alignment is 2.5-3 hours. Always do both sides and alignment together.
Estimated cost: $400-650
Exhaust Manifold Stud Failure (2.5L I4)
Occasional · medium severityTypical onset: 90,000-140,000 mi
Symptoms: Ticking noise from engine that increases with RPM, Exhaust leak smell in cabin with heat on, Visible soot around manifold flange, Failed emissions test due to leak pre-O2 sensor
Fix: Studs corrode and snap at cylinder head. Middle studs most common. Requires manifold removal and extraction of broken studs, often need helicoil inserts. 4-6 hours labor depending on how many studs break during removal. Use anti-seize on reinstall.
Estimated cost: $500-950
Headlight Wiring Harness Melting
Occasional · medium severitySymptoms: One or both low beams intermittent or dead, Melted plastic smell near headlights, Headlight bulbs burn out repeatedly, Flickering headlights
Fix: Factory harness undersized for current draw, connector melts at bulb socket. Multiple NHTSA recalls but not all VINs covered. Requires replacement pigtail or entire harness depending on damage (1-2 hours per side). Upgrade to relayed harness prevents recurrence.
Estimated cost: $150-400
Engine and Transmission Mount Failure
Common · low severityTypical onset: 80,000-120,000 mi
Symptoms: Excessive vibration at idle in drive, Clunk when shifting from reverse to drive, Engine rocks visibly when revving in park, Harsh engagement into gear
Fix: Hydraulic mounts crack and leak fluid. Front mount and transmission mount most common. Replace all three mounts at once (upper strut tower, front, and trans mount) as labor overlaps. Total 3-4 hours for all three. OEM mounts preferred over aftermarket.
Estimated cost: $450-750
Buy the 2.5L four-cylinder with manual transmission only; avoid the 3.5L V6 and CVT combination unless pre-cat fix is documented and you have $5K set aside for transmission replacement.
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.