2001 NISSAN ALTIMA

Typical onset: 80,000-140,000 mi

Symptoms: Blue smoke on cold start or acceleration, Needing 1+ quart every 500-1000 miles, Check engine light with P0420 catalyst efficiency code, Rattling from engine bay at startup

Fix: The pre-cat breaks apart internally and debris scores cylinder walls, destroying piston rings. Requires complete engine rebuild or short block replacement. 12-16 labor hours for experienced tech doing short block swap.

Estimated cost: $2,800-4,500

Typical onset: 90,000-150,000 mi

Symptoms: Transmission fluid looks pink/milky or 'strawberry milkshake' color, Harsh or delayed shifts after engine reaches operating temp, Transmission slipping or not engaging gears, Coolant level dropping with no visible leaks

Fix: Internal cooler in radiator fails, mixing ATF and coolant. Requires radiator replacement, complete transmission flush (multiple cycles), and often transmission rebuild if driven after contamination. External cooler install recommended. 8-12 hours if trans needs rebuild.

Estimated cost: $400-800 (catch it early); $2,200-3,800 (with transmission rebuild)

Typical onset: 70,000-120,000 mi

Symptoms: Clunking when shifting from Park to Drive or Reverse, Excessive vibration at idle in gear, Visible sagging of transmission when inspecting from below, Jerky acceleration from stop

Fix: Rubber mounts deteriorate badly in this generation. Front and rear mounts typically fail together. Straightforward replacement. 2-3 labor hours for both mounts.

Estimated cost: $250-450

Symptoms: No-start condition, cranks but won't fire, Intermittent stalling while driving, especially when hot, Tachometer drops to zero then car dies, P0335 or P0340 codes

Fix: Sensor mounted in bellhousing area fails from heat. When it goes, you're stranded. Part is cheap but requires removing accessories for access. 1.5-2.5 labor hours.

Estimated cost: $180-320

Typical onset: 100,000-150,000 mi

Symptoms: Rough idle and hesitation on acceleration, Poor fuel economy (3-5 MPG drop), Check engine light with P0171/P0174 lean codes, Black carbon buildup visible on sensor element

Fix: MAF sensor gets contaminated from oiled aftermarket air filters or just age. Clean with MAF-specific cleaner first; if that fails, replace. 0.3-0.5 labor hours.

Estimated cost: $15-25 (cleaning); $180-280 (replacement)

Typical onset: 60,000+ mi

Symptoms: Metallic rattling from engine bay on startup and acceleration, Noise disappears once engine fully warmed up, Sound intensifies over bumps

Fix: Heat shields rust and mounting tabs break. Can remove shields entirely or re-secure with high-temp wire or new hardware. 0.5-1.0 labor hours if removing.

Estimated cost: $80-150