The BMW N46B20CB is a 1,995 cc, inline-four petrol engine produced between 2007 and 2011. It features DOHC, 16-valve architecture and BMW's Valvetronic II variable valve lift system, delivering 125 kW (170 PS) at 6,400 rpm and 210 Nm of torque at 3,600 rpm. Valvetronic enables throttle-less air intake for smooth, linear throttle response and improved fuel efficiency.
Fitted primarily to the E90 320i, E87 120i, and E60 520i models, the N46B20CB was engineered for refined performance and responsive driving dynamics in entry-level luxury applications. Emissions compliance was achieved through a close-coupled three-way catalytic converter and precise air-fuel control, allowing the engine to meet Euro 4 standards across its production run.
One documented concern is premature wear of the Valvetronic eccentric shaft sensor, which can lead to erratic idle and engine stalling. This issue, highlighted in BMW Service Information Bulletin 11 04 03, is typically caused by heat exposure and electrical contact degradation. Later production revisions included updated sensor materials and shielding to improve longevity.
Production years 2007–2011 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/5680).
The BMW N46B20CB is a 1,995 cc inline-four petrol engine engineered for compact and mid-size models (2007–2011). It combines Valvetronic II variable valve lift with DOHC 16-valve architecture to deliver high-revving performance and precise throttle response. Designed to meet Euro 4 emissions standards, it balances driver engagement with everyday usability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,995 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 84.0 mm × 90.0 mm | |
| Power output | 125 kW (170 PS) @ 6,400 rpm | |
| Torque | 210 Nm @ 3,600 rpm | |
| Fuel system | Sequential multipoint fuel injection (ME 7.2 ECU) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 11.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Double-row roller chain (non-interference) | |
| Oil type | BMW Longlife-01 (SAE 5W-30) | |
| Dry weight | 140 kg |
The Valvetronic II system enables throttle-less air intake for smooth, linear power delivery but requires strict adherence to 24-month or 24,000 km service intervals to prevent eccentric shaft sensor and motor wear. BMW Longlife-01 (5W-30) oil is essential to maintain hydraulic actuator integrity within the Valvetronic mechanism. Extended idling and short trips can accelerate sensor degradation due to thermal cycling. Fuel system cleanliness is critical—low-quality petrol can lead to injector coking and reduced valve lift precision. The ME 7.2 ECU is sensitive to battery voltage; always use a stable power supply during diagnostics. Pre-2009 models should verify sensor calibration per BMW SIB 11 04 03.
Oil Specs: Requires BMW Longlife-01 (5W-30) specification (BMW SIB 11 04 03). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 4 certification applies to all 2007–2011 models (VCA Type Approval #VCA/EMS/5680).
Power Ratings: Measured under SAE J1349 standards. Output assumes premium unleaded (RON 98) fuel quality (BMW TIS Doc. A26011).
BMW Technical Information System (TIS): Docs A26011, A26531, SIB 11 04 03
VCA Type Approval Database (VCA/EMS/5680)
SAE International: J1349 Engine Power Certification Standards
The BMW N46B20CB was used across BMW's E8x, E9x, and E60 platforms with longitudinal mounting. This engine received platform-specific adaptations—revised intake manifolds in the E60 and updated cooling routing in the E90—and from 2011 was succeeded by the N20B20 turbocharged engine in facelifted models, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the front-facing side of the cylinder block, near the exhaust manifold (BMW TIS A26011). The 7th VIN digit indicates engine family ('M' for N46 series). Pre-2009 models have silver valve covers with black plastic cam covers; post-2009 units use black valve covers. Critical differentiation from N43/N45: N46B20CB lacks a throttle body and features a distinctive Valvetronic motor on the cylinder head. Service parts require production date verification—eccentric shaft sensors before 09/2008 are incompatible with later units due to connector redesign (BMW SIB 11 04 03).
The N46B20CB's primary reliability risk is Valvetronic eccentric shaft sensor failure, with elevated incidence in vehicles used for short-trip urban driving. Internal BMW quality reports from 2008 indicated a significant share of pre-2009 units required sensor replacement before 100,000 km, while UK VCA field data links erratic idle complaints in E90 320i models to sensor degradation. Frequent thermal cycling and voltage fluctuations increase wear on early-design sensors, making adherence to service intervals and use of stable electrical systems critical.
Analysis derived from BMW technical bulletins (2007-2012) and UK VCA field reliability reports (2010-2015). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW N46B20CB.
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