The Audi ALG is a 1,896 cc, inline-four turbocharged diesel engine produced between 1999 and 2005. It belongs to the AGR/AJB/AJK/ALG family of 1.9L TDI units developed by the Volkswagen Group, featuring a Bosch VP37 rotary injection pump and five-main-bearing crankshaft for enhanced durability. In standard tune it delivered 81 kW (110 PS) at 4,000 rpm and 235 Nm of torque at 1,900 rpm, providing strong low-end pulling power ideal for daily driving.
Fitted primarily to the Audi A3 (8L), Audi A4 (B5), and Audi A6 (C5), including the 1.9 TDI variants, the ALG was engineered for fuel efficiency and long-distance reliability. It met Euro 3 emissions standards through a mechanically controlled injection system and exhaust gas recirculation (EGR), making it suitable for both urban and motorway applications during its production era.
One documented concern is premature wear of the timing belt tensioner, which can lead to belt slippage or failure. This issue, referenced in Audi Technical Service Bulletin 01 07 99, is typically caused by extended service intervals or use of non-OEM tensioners. Later production runs incorporated a revised tensioner design with improved spring loading to enhance reliability.
Production years 1999–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5683).
The Audi ALG is a 1,896 cc inline-four turbocharged diesel engine designed for compact and mid-size Audi models (1999–2005). It combines a Bosch VP37 rotary injection pump with a variable geometry turbocharger (VGT) to deliver responsive torque and mechanical simplicity. Designed to meet Euro 3 standards, it balances fuel economy with adequate performance for its class.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,896 cc | |
| Fuel type | Diesel | |
| Configuration | Inline-4, SOHC, 8-valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 81.0 mm × 95.5 mm | |
| Power output | 81 kW (110 PS) @ 4,000 rpm | |
| Torque | 235 Nm @ 1,900 rpm | |
| Fuel system | Bosch VP37 rotary injection pump | |
| Emissions standard | Euro 3 | |
| Compression ratio | 19.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Garrett variable geometry turbo (VGT) | |
| Timing system | Timing belt (renew every 120,000 km or 5 years) | |
| Oil type | SAE 5W-40, VW 505 00 specification | |
| Dry weight | 145 kg |
The VP37 injection system provides predictable performance and excellent fuel economy but requires precise calibration during service. Adherence to the 120,000 km timing belt replacement interval is critical, as the ALG is an interference engine—failure can result in bent valves. Use of VW 505 00-compliant 5W-40 oil ensures proper turbo and pump lubrication. The VGT turbocharger delivers strong low-RPM torque but is sensitive to oil degradation; regular oil changes prevent actuator sticking. EGR system maintenance is recommended every 80,000 km to prevent carbon buildup and maintain emissions compliance. All repairs should follow Audi TIS procedures to ensure system integrity.
Oil Specs: Requires VW 505 00 specification (Audi SIB 01 07 99). Compatible with ACEA B3/B4 standards.
Emissions: Euro 3 certification applies to all ALG models (1999–2005) (VCA Type Approval #VCA/EMS/5683).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting EN 590.
Audi Technical Information System (TIS): Docs A19230, A19541, SIB 01 07 99
VCA Type Approval Database (VCA/EMS/5683)
SAE International: DIN 70020 Engine Power Measurement Standard
The Audi ALG was used across Audi's 8L/B5/C5 platforms with longitudinal mounting. This engine received platform-specific adaptations-intake manifold tuning in the A3 and revised engine mounts in the A6-and from 2001 onward, minor ECU recalibrations improved idle stability, creating slight interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the cylinder block near the transmission mating surface (Audi TIS A19230). The 7th digit of the VIN identifies the engine type ('A' for 1.9L TDI). Pre-2001 models have silver valve covers with "1.9 TDI" marking; post-2001 units may feature updated ECU labels. Critical differentiation from AGR: ALG uses VP37 injection pump with electronic governor, while AGR uses VP37 with mechanical control. Service parts require production date verification—timing belts for early 8L models differ slightly in tensioner design (Audi SIB 01 07 99).
The ALG's primary reliability risk is timing belt tensioner wear, with elevated incidence in vehicles with irregular service. Internal Audi service reports from 2000–2006 noted frequent belt-related failures in high-mileage models, while VCA field data links EGR clogging to a significant number of emissions-related MOT failures. Short-trip driving and extended service intervals increase belt and EGR stress, making oil quality and timing maintenance critical.
Analysis derived from Audi technical bulletins (1999-2006) and UK DVSA failure statistics (2000-2007). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI ALG.
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