2003 INFINITI M45

The 2003 INFINITI M45 is a full-size luxury sedan known for its powerful engine, comfortable ride, and distinctive styling. It came with a single engine option: a 4.5-liter V8 (VK45DE) producing 340 horsepower and 333 lb-ft of torque, paired with a 5-speed automatic transmission. Owners generally appreciate the M45’s performance and comfortable interior but often note its age-related maintenance needs and fuel economy as downsides.

Engine

4.5L V8 (VK45DE)

• Timing Chain Tensioner Failure
  • Description/Symptoms: Rattling noise, especially on startup. Can lead to more serious engine damage if left unaddressed.
  • Solution: Replace the timing chain tensioners.
  • Estimated Cost to Fix: $800 - $1500+
  • Recalls: None Found
• Valve Cover Gasket Leaks
  • Description/Symptoms: Oil leaks around the valve covers, leading to burning oil smell and potentially low oil levels.
  • Solution: Replace the valve cover gaskets.
  • Estimated Cost to Fix: $300 - $600
  • Recalls: None Found

Transmission

5-Speed Automatic Transmission

• Slipping/Harsh Shifting
  • Description/Symptoms: Transmission slips between gears, has harsh or delayed shifts, or fails to engage properly.
  • Solution: Fluid flush/replacement may temporarily improve symptoms, but often requires a full transmission rebuild or replacement.
  • Estimated Cost to Fix: $300 (fluid flush) to $2500-$4000+ (rebuild/replacement)
  • Recalls: None Found

Suspension

• Strut and Shock Absorber Failure
  • Description/Symptoms: Bumpy ride, poor handling, excessive bouncing.
  • Solution: Replace worn struts and shock absorbers.
  • Estimated Cost to Fix: $400 - $1000+ (depending on parts and labor)
  • Recalls: None Found
• Control Arm Bushing Wear
  • Description/Symptoms: Clunking noises from the suspension, especially over bumps. Poor alignment and handling.
  • Solution: Replace worn control arm bushings or the entire control arm.
  • Estimated Cost to Fix: $300 - $800+ (depending on the specific bushing and labor)
  • Recalls: None Found

Electrical

• Battery Drain Issues
  • Description/Symptoms: The battery drains quickly, especially when the car is not in use. Could be a parasitic draw.
  • Solution: Diagnose and repair the source of the electrical drain. Common culprits can be alternators, relays or aftermarket accessories
  • Estimated Cost to Fix: $100-$500+
  • Recalls: None Found
• Climate Control Issues
  • Description/Symptoms: Problems with the automatic climate control system, such as failure to blow cold air or inconsistent temperature regulation.
  • Solution: Can be caused by a faulty blend door actuator, refrigerant leak, or compressor issue.
  • Estimated Cost to Fix: $100-$1000+
  • Recalls: None Found

Exterior

• Headlight Lens Clouding/Yellowing
  • Description/Symptoms: Headlight lenses become cloudy or yellowed, reducing visibility at night.
  • Solution: Polish/restore the headlight lenses or replace the headlight assemblies.
  • Estimated Cost to Fix: $50-$200 (polishing) to $300-$800+ (replacement)
  • Recalls: None Found

Interior

• Navigation System Failure
  • Description/Symptoms: The factory navigation system stops working or experiences glitches.
  • Solution: The unit may need to be replaced or repaired by a specialist. Given the age of the system, this can be difficult or impractical.
  • Estimated Cost to Fix: $200 - $1000+
  • Recalls: None Found
• Sunroof Issues
  • Description/Symptoms: Sunroof may not open or close properly, gets stuck, or leaks.
  • Solution: Clean and lubricate the sunroof tracks and seals, or repair/replace faulty components.
  • Estimated Cost to Fix: $50 - $500+
  • Recalls: None Found

Summary: The 2003 INFINITI M45, while a powerful and luxurious sedan, is now over 20 years old, so owners should expect age-related maintenance issues. Common complaints revolve around engine maintenance (specifically leaks and timing chain issues), transmission wear, suspension components, and electrical glitches. The severity of these issues ranges from relatively inexpensive fixes (gaskets, polishing headlights) to more costly repairs (transmission rebuild, timing chain replacement). The estimated cost can be as little as $50 for minor repairs, and go up to $4000+ for more intense issues.