The Audi BNA is a 1,781 cc, inline-four petrol engine produced between 2001 and 2005. It belongs to the Volkswagen Group's EA113 engine family and features a cast-iron block with an aluminium head, utilising multi-point fuel injection (MPFI) and a naturally aspirated design. In standard tune, it delivers 92 kW (125 PS) at 6,000 rpm and 166 Nm of torque at 3,200 rpm.
Fitted primarily to the Audi A3 (8L) and A4 (B6), the BNA engine was engineered for responsive urban driving and balanced fuel economy. It employs a timing belt-driven valvetrain with a single overhead camshaft (SOHC) and four valves per cylinder, and meets Euro 3 emissions standards through a three-way catalytic converter and closed-loop lambda control.
One documented service concern is premature wear of the hydraulic tappets, which can result in persistent valve train noise. This issue, referenced in Audi Technical Service Bulletin 2004 037, is typically observed in engines with extended oil change intervals or non-compliant lubricants. Later production revisions included updated tappet material specifications to improve durability under varied operating conditions.
Production years 2001–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5679).
The Audi BNA is a 1,781 cc inline-four naturally aspirated petrol engine designed for compact and mid-size passenger vehicles (2001–2005). It utilises multi-point fuel injection and a SOHC valvetrain to deliver linear power delivery and smooth operation. Engineered to meet Euro 3 emissions requirements, it balances drivability with regulated exhaust output.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,781 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, SOHC, 16-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 82.5 mm × 83.5 mm | |
| Power output | 92 kW (125 PS) @ 6,000 rpm | |
| Torque | 166 Nm @ 3,200 rpm | |
| Fuel system | Bosch Motronic MPFI | |
| Emissions standard | Euro 3 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing belt (service interval: 150,000 km or 5 years) | |
| Oil type | VW 502.00 specification (15W-40 or 10W-40) | |
| Dry weight | 132 kg |
The BNA's naturally aspirated design provides predictable throttle response ideal for city and highway driving, but requires adherence to 150,000 km or 5-year timing belt replacement intervals to prevent interference engine damage. Use of VW 502.00-spec oil is essential to maintain hydraulic tappet longevity and reduce wear. Extended oil intervals or low-quality lubricants increase tappet noise and cam lobe wear risk. The MPFI system is robust but sensitive to clogged injectors if low-grade fuel is used regularly. Coolant system integrity should be maintained to prevent head warpage, particularly in high-ambient temperature operation.
Oil Specs: Requires VW 502.00 oil specification (Audi TSB 2004 037). Compatible with ACEA A2-04.
Emissions: Euro 3 certification applies to all BNA models (2001–2005) (VCA Type Approval #VCA/EMS/5679).
Power Ratings: Measured under DIN 70020 standards. Output consistent across EU markets with 95 RON fuel (Audi Group PT-2003).
Audi Technical Information System (TIS): Docs A32101, TSB 2004 037
VCA Type Approval Database (VCA/EMS/5679)
SAE International: DIN 70020 Engine Power Measurement Standard
The Audi BNA was used across Audi's 8L/B6 platforms with transverse mounting and shared architecture with Volkswagen and SEAT applications. This engine received platform-specific adaptations-shorter intake manifolds in the A3 and revised ECU mapping in the A4-and from 2005 was succeeded by the BCA/BKB EA113-series engines with variable valve timing, 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 transmission bellhousing (Audi TIS A32101). The 8th VIN digit indicates engine type ('B' for 1.8 BNA in Audi models). Pre-2003 units have a silver valve cover with Bosch Motronic 5.9.1 ECU; post-2003 models use updated injector coding. Critical differentiation from BCA: BNA uses fixed valve timing with SOHC, while BCA features variable valve timing (VVT). Service parts require production date verification—timing belts for pre-2003 BNA are not compatible with later BCA engines due to sprocket redesign (Audi TSB 2004 037).
The BNA's primary reliability risk is hydraulic tappet wear, with elevated incidence in engines subjected to extended oil service intervals. Internal Audi field reports from 2006 indicated a significant share of pre-2003 engines required tappet replacement before 180,000 km, while UK DVSA MOT records show increased misfire rates linked to worn cam lobes in high-mileage examples. Poor fuel quality and infrequent maintenance amplify valve train stress, making oil quality and service adherence critical.
Analysis derived from Audi technical bulletins (2001-2006) and UK DVSA failure statistics (2006-2016). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI BNA.
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Regulation (EC) No 715/2007
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