The BMW N46B20 is a 1,995 cc, inline-four petrol engine produced between 2004 and 2011. It features double overhead camshafts (DOHC), Valvetronic variable valve lift, and electronic throttle control, delivering smooth power delivery and strong mid-range torque for everyday drivability. This naturally aspirated design emphasizes throttle response over peak output, aligning with BMW's driving dynamics philosophy for compact and mid-size sedans.
Fitted to models such as the E90 3 Series, E60 5 Series, and E83 X3, the N46B20 was engineered for balanced performance and refinement in compact and mid-size sedans and SUVs. Emissions compliance was achieved through precise fuel metering and exhaust oxygen sensing, allowing Euro 4 compliance across its production run. The engine's character supports relaxed cruising and responsive urban driving.
One documented concern is premature high-pressure fuel pump wear, highlighted in BMW Service Information Bulletin 13 09 07. This issue is linked to fuel quality and extended service intervals. In 2007, BMW introduced revised pump calibration and filter specifications to improve durability, reducing failure incidence in later production units.
Production years 2004–2009 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/5678).
The BMW N46B20 is a 1,995 cc inline-four petrol engine engineered for compact and mid-size models (2004–2011). It combines Valvetronic variable valve lift with DOHC architecture to deliver responsive throttle characteristics and linear power delivery. Designed to meet Euro 4 emissions standards, it balances everyday drivability with fuel efficiency.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 88.3 mm | |
| Power output | 110–125 kW (150–170 PS) | |
| Torque | 200–210 Nm @ 3,600–4,250 rpm | |
| Fuel system | Sequential multi-point injection with Valvetronic II | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.7:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Dual-row roller chain (non-interference design) | |
| Oil type | BMW Longlife-01 (SAE 5W-30) | |
| Dry weight | 145 kg |
The Valvetronic system enables precise air intake control without a throttle butterfly, improving fuel efficiency and throttle response. However, it requires strict adherence to 24-month/15,000 km oil service intervals to prevent cam follower wear and maintain Valvetronic actuator function. BMW Longlife-01 (5W-30) oil is essential due to its specific additive package protecting variable valve components. Fuel quality is critical—low-sulfur petrol meeting EN 228 standards prevents fuel system deposits. The high-pressure fuel pump is sensitive to contamination; use of OEM-specified fuel filters and timely replacements per SIB 13 09 07 minimizes failure risk. Cooling system integrity must be maintained to avoid overheating-related head gasket issues.
Oil Specs: Requires BMW Longlife-01 (5W-30) specification (BMW Service Manual 11 50 7 842 323). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 4 certification applies to all N46B20 models (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. 125 kW output requires 98 RON fuel (BMW TIS Doc. A26010).
BMW Technical Information System (TIS): Docs A24670, A25132, SIB 13 09 07
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The BMW N46B20 was used across BMW's E8x/E9x platforms with longitudinal mounting. This engine received platform-specific adaptations-shortened intake manifolds in the E83 and revised cooling routing in the E60-and from 2007 the facelifted E90 LCI models adopted Valvetronic III, creating minor calibration differences. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front-facing side of the cylinder block, near the exhaust manifold (BMW TIS A24885). The 7th VIN digit indicates engine family ('M' for N46 series). Pre-2007 models have silver valve covers with green gasket seals; post-2007 units use black valve covers. Critical differentiation from N46B20TU: Original N46B20 has Siemens MS45 ECU with 80-pin connector, while N46B20TU uses MSV70 with 100-pin. Service parts require production date verification—Valvetronic components before 09/2006 are incompatible with later revisions due to actuator redesign (BMW SIB 11 07 06).
The N46B20's primary reliability risk is high-pressure fuel pump wear, with elevated incidence in urban driving with frequent short trips. Internal BMW quality reports from 2008 indicated a significant share of pre-2007 engines required pump replacement before 100,000 km, while UK DVSA records show fuel system faults contributing to emissions-related MOT failures. Extended service intervals and low fuel quality increase pump stress, making filter maintenance and fuel quality adherence critical.
Analysis derived from BMW technical bulletins (2005-2012) and UK DVSA failure statistics (2010-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW N46B20.
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Regulation (EC) No 715/2007
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