Post
Research the Car Logo

2003 BMW 745i

Posted
By Research the Car 5 min read

The 2003 BMW 745i marked a significant shift in BMW’s design language and technology. Powered by the N62B44 4.4L V8 engine, it produced 325 horsepower and 330 lb-ft of torque. The 745i was praised for its smooth ride, luxurious interior, and advanced features like iDrive. However, it also faced criticism for its complex electronics and sometimes controversial styling. People liked the comfort, performance, and prestige associated with owning a BMW flagship sedan. Dislikes often centered around the high maintenance costs, electrical gremlins, and the steep learning curve associated with the iDrive system. The 745i only had one engine option, but the 745Li had an extended wheelbase.

Engine

N62B44 4.4L V8

  • Coolant Leaks
    • Description/Symptoms: Coolant leaks can occur from several areas, including the valley pan gasket (located under the intake manifold), water pump, and coolant hoses. Symptoms include low coolant levels, overheating, and visible coolant pooling under the vehicle.
    • Solution: Replacing the faulty gasket, water pump, or hose. The valley pan replacement is labor-intensive.
    • Estimated Cost to Fix: Valley pan gasket: $1000 - $2000+. Water pump replacement: $500 - $1000+. Hose replacement: $100 - $500+.
    • Recalls: None Found
  • Valve Stem Seal Failure
    • Description/Symptoms: The valve stem seals are prone to drying out and cracking, leading to oil consumption. Symptoms include blue smoke from the exhaust, especially upon startup.
    • Solution: Replacing the valve stem seals. This is a labor-intensive repair that often requires removing the cylinder heads.
    • Estimated Cost to Fix: $2500 - $5000+
    • Recalls: None Found
  • Oil Leaks
    • Description/Symptoms: Oil leaks are common from the valve cover gaskets, oil pan gasket, and rear main seal. Visible oil leaks around the engine and low oil levels are common symptoms.
    • Solution: Replacing the leaking gaskets or seals.
    • Estimated Cost to Fix: Valve cover gaskets: $300 - $800+. Oil pan gasket: $500 - $1200+. Rear main seal: $800 - $2000+.
    • Recalls: None Found
  • Alternator Failure
    • Description/Symptoms: Intermittent voltage drops, failing electronics, and eventually a dead battery.
    • Solution: Replace the alternator.
    • Estimated Cost to Fix: $500 - $1000+
    • Recalls: None Found

Transmission

ZF 6HP26 6-Speed Automatic

  • Slipping or Harsh Shifting
    • Description/Symptoms: The ZF 6HP26 transmission can experience slipping between gears, harsh or delayed shifting, or complete failure. These issues often stem from deteriorated transmission fluid, worn valve body components, or internal damage to the clutch packs.
    • Solution: Transmission fluid flush and filter replacement (may provide temporary relief), valve body replacement or rebuild, or complete transmission rebuild or replacement.
    • Estimated Cost to Fix: Fluid flush and filter: $300 - $500. Valve body replacement: $1000 - $2500. Transmission rebuild: $3000 - $6000. Transmission replacement: $5000 - $8000+.
    • Recalls: None Found
  • Mechatronic Sleeve Leak
    • Description/Symptoms: The mechatronic sleeve, which seals the electrical connector to the transmission, can leak fluid. This can cause shifting problems or electrical faults.
    • Solution: Replacing the mechatronic sleeve and associated seals.
    • Estimated Cost to Fix: $300 - $800
    • Recalls: None Found

Suspension

  • Air Suspension Failure
    • Description/Symptoms: The 745i features an air suspension system that can be prone to leaks and component failures. Symptoms include the car sitting low on one or more corners, suspension warning lights, and a noisy air compressor.
    • Solution: Replacing the leaking air struts (air springs), air compressor, or ride height sensors.
    • Estimated Cost to Fix: Air strut replacement: $800 - $2000+ per strut. Air compressor replacement: $500 - $1200+. Ride height sensor: $200 - $500.
    • Recalls: None Found
  • Control Arm Bushing Wear
    • Description/Symptoms: Worn control arm bushings can cause clunking noises, especially over bumps, and can affect handling and alignment.
    • Solution: Replacing the worn control arm bushings or the entire control arm assembly.
    • Estimated Cost to Fix: Bushing replacement: $200 - $500 per arm. Control arm replacement: $400 - $800 per arm.
    • Recalls: None Found

Electrical

  • iDrive Malfunctions
    • Description/Symptoms: The iDrive system can experience various malfunctions, including screen freezing, system reboots, and loss of functionality.
    • Solution: Software updates, replacement of the iDrive control module (CCC unit), or repair of faulty wiring.
    • Estimated Cost to Fix: Software update: $100 - $300. CCC unit replacement: $800 - $2500+.
    • Recalls: None Found
  • Battery Drain Issues
    • Description/Symptoms: The 745i is known for experiencing parasitic battery drain, which can lead to a dead battery if the car sits for an extended period. This is often caused by a faulty module that is not shutting down properly.
    • Solution: Identifying and replacing the faulty module or repairing the associated wiring. This requires specialized diagnostic equipment and knowledge.
    • Estimated Cost to Fix: $200 - $1000+ depending on the module.
    • Recalls: None Found
  • Sensor Failures
    • Description/Symptoms: Numerous sensors throughout the car can fail, leading to warning lights and drivability issues. Common culprits include oxygen sensors, crankshaft position sensors, and camshaft position sensors.
    • Solution: Replacing the faulty sensor.
    • Estimated Cost to Fix: $150 - $500+ per sensor.
    • Recalls: None Found

Exterior

  • Door Lock Actuator Failure
    • Description/Symptoms: Door lock actuators can fail, preventing the doors from locking or unlocking properly.
    • Solution: Replacing the faulty door lock actuator.
    • Estimated Cost to Fix: $200 - $500 per door.
    • Recalls: None Found

Interior

  • Sunroof Issues
    • Description/Symptoms: The sunroof mechanism can be prone to failure, causing it to get stuck or make excessive noise.
    • Solution: Repair or replacement of the sunroof mechanism.
    • Estimated Cost to Fix: $500 - $1500+
    • Recalls: None Found
  • Seat Motor Failure
    • Description/Symptoms: The power seat motors can fail, preventing the seats from adjusting properly.
    • Solution: Replacing the faulty seat motor.
    • Estimated Cost to Fix: $300 - $800 per motor.
    • Recalls: None Found

Summary

The 2003 BMW 745i, while offering a luxurious and technologically advanced driving experience, is prone to a variety of issues that can be both costly and frustrating to address. Engine issues like coolant and oil leaks, transmission problems such as slipping and harsh shifting, and electrical gremlins, particularly with the iDrive system, are frequently reported. The air suspension is another common source of problems. These issues can range in severity, with some requiring relatively inexpensive fixes while others can necessitate major repairs costing thousands of dollars. Prospective buyers should be aware of these potential pitfalls and budget accordingly for maintenance and repairs.

BMW, 745i
BMW 745i 2003
This post is licensed under CC BY 4.0 by the author.