2004 BMW 745Li

The 2004 BMW 745Li is a full-size luxury sedan that represented BMW’s flagship vehicle at the time. It came equipped with a 4.4L N62 V8 engine producing 325 horsepower and 330 lb-ft of torque. This engine was paired with a 6-speed automatic transmission. Owners often praised the 745Li for its innovative technology, comfortable ride, and powerful engine, while common complaints centered around its complex electronics, high maintenance costs, and somewhat polarizing styling.

Engine

N62B44 4.4L V8

• Valve Stem Seal Failure
  • Description/Symptoms: Excessive oil consumption, blue smoke upon startup, especially after the car has been sitting for a while.
  • Solution: Replacing the valve stem seals. This is a labor-intensive job as it often involves removing the cylinder heads.
  • Estimated Cost to Fix: $3,000 - $5,000+
  • Recalls: None Found
• Coolant Leaks (Valley Pan)
  • Description/Symptoms: Coolant loss, overheating, coolant smell. The valley pan, located under the intake manifold, is prone to cracking and leaking.
  • Solution: Replacing the valley pan and associated gaskets. This requires removing the intake manifold.
  • Estimated Cost to Fix: $1,500 - $3,000+
  • Recalls: None Found
• Alternator Bracket Oil Leaks
  • Description/Symptoms: Oil leaking from the front of the engine, often mistaken for a front crankshaft seal leak. The alternator bracket uses an o-ring to seal against the engine block. This o-ring can harden and leak over time.
  • Solution: Replace the alternator bracket gasket or o-ring.
  • Estimated Cost to Fix: $500 - $1,000+
  • Recalls: None Found
• Oil Filter Housing Gasket Leak
  • Description/Symptoms: Oil leaking from the oil filter housing, often dripping down the side of the engine block.
  • Solution: Replace the oil filter housing gasket.
  • Estimated Cost to Fix: $300 - $600
  • Recalls: None Found

Transmission

ZF 6HP26 6-Speed Automatic

• Slipping or Harsh Shifting
  • Description/Symptoms: Delayed engagement, harsh shifts, or slipping between gears, especially when the transmission is cold. Can also cause a “Transmission Fault” warning.
  • Solution: Could be caused by low fluid, a faulty mechatronic unit (valve body), or worn clutches. A fluid change might help in early stages, but often requires replacing the mechatronic unit or a full transmission rebuild.
  • Estimated Cost to Fix: Fluid Change: $300 - $500. Mechatronic Unit Replacement: $1,500 - $3,000+. Transmission Rebuild/Replacement: $3,000 - $6,000+
  • Recalls: None Found
• Torque Converter Failure
  • Description/Symptoms: Shuddering at low speeds, especially under light acceleration. Can also cause a “Transmission Fault” warning.
  • Solution: Replacing the torque converter.
  • Estimated Cost to Fix: $1,500 - $3,000+
  • Recalls: None Found

Suspension

• Air Suspension Failure
  • Description/Symptoms: Vehicle sagging on one or more corners, “Self-Leveling Suspension Inactive” warning on the iDrive screen, compressor running constantly.
  • Solution: Leaks in the air springs (struts), a faulty air compressor, or a faulty valve block. Replacing the affected air springs, compressor, or valve block.
  • Estimated Cost to Fix: Air Spring Replacement (per strut): $800 - $2,000+. Air Compressor Replacement: $600 - $1,200+. Valve Block Replacement: $400 - $800+.
  • Recalls: None Found
• Control Arm Bushing Failure
  • Description/Symptoms: Clunking noises from the suspension, especially over bumps. Vague steering.
  • Solution: Replacing the worn control arm bushings or the entire control arm.
  • Estimated Cost to Fix: Bushing Replacement (per control arm): $200 - $500. Control Arm Replacement (per arm): $400 - $800+
  • Recalls: None Found

Electrical

• iDrive Malfunctions
  • Description/Symptoms: The iDrive system freezing, rebooting, or displaying error messages. Can also cause issues with other systems controlled by iDrive, such as navigation, climate control, and entertainment.
  • Solution: Software updates, replacement of the iDrive computer (CCC unit), or repair of faulty wiring.
  • Estimated Cost to Fix: Software Update: $100 - $300. CCC Unit Replacement: $1,000 - $2,500+
  • Recalls: None Found
• Battery Drain
  • Description/Symptoms: Dead battery, especially after the car has been sitting for a few days. Can be caused by a variety of issues, including a faulty alternator, a parasitic drain from a module that isn’t shutting down properly, or a failing battery.
  • Solution: Diagnosing and repairing the source of the battery drain. This can involve testing the alternator, checking for parasitic draws, and testing the battery.
  • Estimated Cost to Fix: Battery Replacement: $200 - $500. Alternator Replacement: $500 - $1,000+. Parasitic Drain Diagnosis and Repair: Varies widely depending on the source of the drain.
  • Recalls: None Found
• Comfort Access Issues
  • Description/Symptoms: Comfort Access system failing to unlock or lock the doors when the key fob is near the vehicle, or the push-button start not working.
  • Solution: Replacing faulty door handle sensors, key fobs, or the Comfort Access control module.
  • Estimated Cost to Fix: Door Handle Sensor Replacement (per handle): $300 - $600+. Key Fob Replacement: $300 - $500+. Control Module Replacement: $500 - $1,000+
  • Recalls: None Found
• Instrument Cluster Failure
  • Description/Symptoms: Pixels going out on the instrument cluster. Dimming of the Instrument Cluster
  • Solution: Have the instrument cluster replaced or repaired.
  • Estimated Cost to Fix: $500 - $1500+
  • Recalls: None Found

Exterior

• Door Lock Actuator Failure
  • Description/Symptoms: Door locks failing to lock or unlock, either manually or with the key fob.
  • Solution: Replacing the faulty door lock actuator.
  • Estimated Cost to Fix: $300 - $600 (per door)
  • Recalls: None Found

Interior

• Headliner Sagging
  • Description/Symptoms: The headliner fabric detaching from the backing and sagging down. This is a common issue in older vehicles with glued headliners.
  • Solution: Replacing the headliner fabric.
  • Estimated Cost to Fix: $500 - $1,200+
  • Recalls: None Found
• Sunroof Issues
  • Description/Symptoms: Sunroof failing to open or close properly, making excessive noise, or leaking.
  • Solution: Repairing or replacing the sunroof motor, tracks, or seals.
  • Estimated Cost to Fix: Motor Replacement: $300 - $600. Track/Seal Repair/Replacement: $400 - $1,000+
  • Recalls: None Found

Summary

The 2004 BMW 745Li is a technologically advanced and luxurious vehicle, but it is also known for its high maintenance costs and potential for expensive repairs. Many of the common issues stem from its complex electronics and aging components. Engine issues like valve stem seal failures and coolant leaks can be particularly costly. Suspension issues, especially with the air suspension, are also prevalent and can be expensive to fix. While some repairs may be relatively minor, the potential for major, costly repairs should be carefully considered when purchasing or owning this vehicle.