BMW N73 6.0 V12: Specs, Engine Code, ECUs & Maintenance
BMW · Engine information · U.S. & Canada
N73
6.0 V12 · Effortless power, intricate electronics
The naturally aspirated N73 makes its character through twelve small, closely spaced power strokes. Direct injection and variable valve lift add sophistication beneath the smooth delivery—and explain why its electronics involve more than a single ECU.
Architecture
- Engine code
- N73B60
- Layout
- 60° V12 · DOHC · 48 valves
- Block / heads
- Aluminium / aluminium
- Bore × stroke
- 89.0 × 80.0 mm
- Aspiration
- Naturally aspirated
- Cam drive
- Timing chains
Fuel & valve control
- Injection
- Gasoline direct injection
- Fuel pressure
- 50–120 bar
- Valve lift
- Valvetronic
- Cam timing
- Double VANOS
- Fuel
- Premium unleaded
- Main controllers
- Two Bosch MED9.2.1 DMEs
Engine controllers · Bosch MED9.2.1 + supporting modules
The N73 uses five cooperating engine-control modules: two main DMEs, two injector-driver modules and one Valvetronic controller. A fault in a power supply, injector driver or valve-lift module can resemble a main-ECU failure, so the complete system needs to be identified.
| Controller | Applications & timing | Technical distinction |
|---|---|---|
| MED9.2.1 · DME 1 and DME 2 | N73B60 in E65/E66 760 models | Bank-specific injection/ignition management, sensor evaluation and coordinated engine torque. |
| Two HDEV injector modules | One high-pressure injector-driver module per cylinder bank | Activate the direct injectors under DME command; separate from the main MED9.2.1 units. |
| Valvetronic controller | Shared valve-lift control module | Operates intake-valve lift in cooperation with both DMEs; supply and communication checks are part of diagnosis. |
Match both DME part numbers, vehicle coding and immobilizer information. MED9.2.1 should not be confused with the ME9.2-series controllers used on port-injected BMW engines.
Selected U.S. & Canadian vehicles
| Model | Chassis | Model years | Engine / factory output |
|---|---|---|---|
| 760Li | E66 | 2003–2008 | N73B60 · 438 hp / 444 lb-ft |
| 760i | E65 | 2004–2006 · U.S. offering | N73B60 · 438 hp / 444 lb-ft |
The long-wheelbase 760Li is the principal North American application. Model availability and quoted metric ratings differ by market.
Common issues & key risks
High-pressure pump diaphragms. A leaking diaphragm can feed fuel into the vent connection and cause rough running. Compare both banks’ pressures and follow BMW’s pump-leak test.
Coolant-transfer pipe. Ageing internal seals can cause persistent coolant loss. Pressure-test and inspect the transfer pipe before assuming the radiator or head gasket is responsible.
Oil leaks & consumption. Cover gaskets, crankcase ventilation and valve-stem seals deserve inspection when oil use increases. Diagnose smoke and crankcase pressure before committing to seal replacement.
Valvetronic faults. Uneven running or valve-lift faults require checks of motors, eccentric-shaft feedback, wiring and adaptations on both banks. Confirm power supply before condemning a control module.
Plugs, coils & intake leaks. Age-related ignition and sealing faults can mimic more expensive fuel-system failures. Use cylinder-specific misfire data and intake-leak testing to narrow the repair.
Keep it consistent: Maintain the specified oil approval and monitor both oil and coolant levels. Correct diagnosis of all five control modules helps avoid expensive parts replacement by guesswork.
References
| Topic | Source |
|---|---|
| U.S. specifications | BMW USA: 2003 760Li press kit |
| Engine systems | BMW E65/E66 technical training, N73 diagnosis |
| Control architecture | BMW N73 engine-management training |
| Fuel-pump diaphragm test | BMW repair instructions · CHARM archive |
| Coolant-pipe seal failure | AGA Tools · V12 coolant-pipe repair |
| Valve-seal service | BMW N73 repair instructions · CHARM archive |
| Photograph | N73B60 · KaiserV2 · CC0 1.0. Wikimedia Commons. |
Model years refer to selected U.S. and Canadian applications. Equipment and software vary by build. Use current BMW service information for diagnosis and repair.
