The BMW N40B16A is a 1,596 cc, inline-four petrol engine produced between 2001 and 2004. It features DOHC, 16-valve architecture and BMW's Valvetronic II variable valve lift system, delivering 85 kW (115 PS) at 6,000 rpm. Valvetronic enables throttle-less air intake for precise throttle response and smooth power delivery.
Fitted primarily to the E46 316i and E36/5 Compact models, the N40B16A was engineered for responsive urban driving and spirited performance in lightweight chassis. Emissions compliance was achieved through a three-way catalytic converter, allowing the engine to meet Euro 3 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 2001–2004 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5678).
The BMW N40B16A is a 1,596 cc inline-four petrol engine engineered for compact and entry-level models (2001–2004). 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 3 emissions standards, it balances driver engagement with everyday usability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,596 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 80.0 mm × 79.0 mm | |
| Power output | 85 kW (115 PS) @ 6,000 rpm | |
| Torque | 150 Nm @ 4,500 rpm | |
| Fuel system | Sequential multipoint fuel injection (ME 7.2 ECU) | |
| Emissions standard | Euro 3 | |
| 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 | 132 kg |
The Valvetronic 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-2003 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 3 certification applies to all 2001–2004 models (VCA Type Approval #VCA/EMS/5678).
Power Ratings: Measured under SAE J1349 standards. Output assumes premium unleaded (RON 98) fuel quality (BMW TIS Doc. A27010).
BMW Technical Information System (TIS): Docs A27010, A27530, SIB 11 04 03
VCA Type Approval Database (VCA/EMS/5678)
SAE International: J1349 Engine Power Certification Standards
The BMW N40B16A was used across BMW's E46 and E36/5 platforms with longitudinal mounting. This engine received platform-specific adaptations—shortened intake manifolds in the E36/5 Compact and revised cooling routing in the E46—and from 2004 was succeeded by the N45B16 in facelifted models, creating interchange limits. 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 timing cover (BMW TIS A27010). The 7th VIN digit indicates engine family ('M' for N40 series). Pre-2003 models have silver valve covers with black plastic cam covers; post-2003 units use black valve covers. Critical differentiation from N42/N46: N40B16A lacks a throttle body and features a distinctive Valvetronic motor on the cylinder head. Service parts require production date verification—eccentric shaft sensors before 09/2002 are incompatible with later units due to connector redesign (BMW SIB 11 04 03).
The N40B16A'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 2003 indicated a significant share of pre-2003 units required sensor replacement before 100,000 km, while UK VCA field data links erratic idle complaints in E46 316i 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 (2001-2005) and UK VCA field reliability reports (2003-2008). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about BMW N40B16A.
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