Here is a detailed description of the BMW E60 M54 (engine code 256S) with ZF 6HP19 automatic gearbox:

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Engine: BMW M54B25 (256S5)

• Engine Code: 256S5 (M54B25)
• Displacement: 2.5L (2494 cc)
• Configuration: Inline 6-cylinder, DOHC, 24-valve
• Fuel System: Electronic Fuel Injection (Bosch ME9.2)
• Valvetronic: No (used in N series, not M54)
• Maximum Power: ~141 kW (190 hp) @ 6000 rpm
• Maximum Torque: ~245 Nm @ 3500 rpm
• Block Material: Aluminum with cast iron sleeves
• Head Material: Aluminum
• Cooling: Water-cooled
• Fuel Type: Petrol
• Drive Type: Rear-wheel drive (RWD)

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Transmission: ZF 6HP19 (6-speed automatic)

• Gearbox Model: ZF 6HP19
• Type: 6-speed automatic transmission with torque converter
• Gear Ratios:
  
• 1st: 4.17
• 2nd: 2.34
• 3rd: 1.52
• 4th: 1.14
• 5th: 0.87
• 6th: 0.69 (overdrive)
• Reverse: 3.40
• 
  
• Torque Rating: Up to ~400 Nm
• Fluid Type: ZF LifeguardFluid 6
• Control: Mechatronic (electro-hydraulic control unit integrated)
• Used In: BMW E60, E90, E83, and others

⚙️ Engine + Gearbox Match

• The M54B25 and ZF 6HP19 combo offers smooth power delivery with good mid-range torque.
• Common in: BMW E60 525i (pre-facelift, around 2003–2005)
• Drivability: Known for linear power, refined shifting, and durable performance if properly maintained.

🛠️ Common Issues to Watch

• M54 Engine:
  
• Valve cover gasket leaks
• DISA valve failure
• Cooling system (water pump, thermostat)
• Oil leaks from oil filter housing
• 
  
• ZF 6HP19 Gearbox:
  
• Mechatronic sleeve leaks
• Jerky shifts if fluid not changed (~60k–80k km recommended despite ''lifetime'' claim)
• Torque converter shudder if fluid is degraded
• 
  

Let me know if you want wiring diagrams, parts compatibility, or retrofit tips!