The Audi BLS is a 1,781 cc, inline-four petrol engine produced between 2005 and 2008. It belongs to the EA113 engine family and features a dual overhead camshaft (DOHC) layout with five valves per cylinder for improved airflow efficiency. Equipped with sequential multi-point fuel injection and a naturally aspirated design, it delivers 85 kW (116 PS) and 165 Nm of torque, providing balanced performance in compact Audi models.
Fitted primarily to the Audi A3 (8P) and SEAT León (1M), the BLS engine was engineered for fuel-efficient urban driving and smooth mid-range responsiveness. It complies with Euro 4 emissions standards through the use of a three-way catalytic converter and closed-loop lambda control system. The engine's design prioritizes reliability and serviceability, with widely available OEM parts and straightforward maintenance procedures.
One documented concern is premature wear of the hydraulic valve lifters, which can result in audible tappet noise under cold start conditions. This issue, referenced in Audi Service Information Bulletin 01 08 05, is attributed to oil flow restrictions in early production units. Audi addressed this with revised lifter design and updated oil change intervals to improve longevity.
Production years 2005–2008 meet Euro 4 standards (VCA UK Type Approval #VCA/EMS/6789).
The Audi BLS is a 1,781 cc inline-four petrol engine developed for transverse-mounted applications in compact platforms (2005–2008). It features five-valve cylinder head technology and sequential fuel injection to optimize low-end torque and throttle response. Designed to meet Euro 4 emissions standards, it balances efficiency with everyday drivability in front-wheel-drive configurations.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,781 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-4, DOHC, 20-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 81.0 mm × 86.4 mm | |
| Power output | 85 kW (116 PS) @ 5,800 rpm | |
| Torque | 165 Nm @ 3,200 rpm | |
| Fuel system | Sequential multi-point fuel injection | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing belt (interval: 120,000 km or 5 years) | |
| Oil type | Audi Longlife 01 (SAE 5W-40) | |
| Dry weight | 135 kg |
The five-valve head provides smooth power delivery and strong mid-range torque but requires strict adherence to 120,000 km or 5-year timing belt service intervals to prevent interference engine damage. Audi Longlife 01 (5W-40) oil is essential for maintaining hydraulic lifter function and camshaft lubrication. Extended short-trip driving may accelerate lifter wear due to inadequate oil warming. The intake manifold and throttle body should be inspected periodically for carbon buildup affecting idle stability. Pre-2006 models should have the updated lifters installed per Audi SIB 01 08 05 to reduce risk of tappet noise. Catalytic converter longevity depends on correct fuel trim and use of unleaded petrol meeting EN 228 standards.
Oil Specs: Requires Audi Longlife 01 (5W-40) specification (Audi SIB 01 08 05). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 4 certification applies to all BLS production models (VCA Type Approval #VCA/EMS/6789).
Power Ratings: Measured under DIN 70020 standards. Output consistent across all markets (Audi TIS Doc. A18721).
Audi Technical Information System (TIS): Docs A18721, A19013, SIB 01 08 05
VCA Type Approval Database (VCA/EMS/6789)
DIN Standards: DIN 70020 Engine Power Measurement
The Audi BLS was used across Audi's 8P and SEAT's 1M platforms with transverse mounting and shared architecture within the Volkswagen Group. This engine received platform-specific adaptations-shorter accessory drives in the A3 and reinforced engine mounts in the León-and from 2007 the facelifted A3 8P adopted the BKB variant with revised intake manifolding, 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 exhaust manifold (Audi TIS A18801). The 7th digit of the VIN identifies the engine family ('A' for 1.8L 20V naturally aspirated). Pre-2006 models have silver cam covers with black valve gaskets; post-2006 units use black cam covers. Critical differentiation from turbo variants: BLS has no intercooler or boost sensor; intake plenum is smaller and lacks a bypass valve. Service parts require production date verification—timing belts for pre-2006 models are incompatible with post-2006 revisions due to lifter redesign (Audi SIB 01 08 05).
The BLS's primary reliability risk is hydraulic valve lifter wear on early builds, with elevated incidence in vehicles used for frequent short trips. Internal Audi quality reports from 2007 noted a significant number of pre-2006 engines requiring lifter replacement, while UK DVSA records indicate a notable share of MOT failures linked to excessive valve train noise in neglected units. Extended service intervals and cold starts increase lifter stress, making adherence to maintenance schedules critical.
Analysis derived from Audi technical bulletins (2005-2008) and UK DVSA failure statistics (2008-2012). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI BLS.
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