The Volkswagen AQD is a 1,896 cc, inline‑four turbo‑diesel engine produced between 2000 and 2005. It features a single overhead camshaft (SOHC) design with 8 valves and a fixed-geometry turbocharger. This robust configuration, part of the ALH/AHU family, delivers 96 kW (130 PS) and 310 Nm of torque, prioritizing low-end pulling power and mechanical simplicity.
Fitted to models such as the Mk4 Golf, Bora, and early Audi A3 8L, the AQD was engineered for dependable, economical transportation with strong towing capability. Emissions compliance was achieved under Euro 3 standards through the use of an oxidation catalyst and exhaust gas recirculation (EGR).
One documented concern is premature failure of the tandem pump, which integrates the vacuum pump and fuel lift pump. This issue, addressed in Volkswagen Technical Service Bulletin 2015003/1, can lead to loss of brake booster vacuum and/or fuel starvation. The root cause is often attributed to internal seal degradation or bearing wear within the pump assembly.
Volkswagen
Production years 2000–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5680).
The Volkswagen AQD is a 1,896 cc inline‑four turbo‑diesel engineered for compact models (2000-2005). It combines SOHC 8-valve architecture with a fixed-geometry turbocharger to deliver strong low-end torque and exceptional durability. Designed to meet Euro 3 standards, it prioritizes mechanical simplicity and fuel economy over peak power.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,896 cc | |
| Fuel type | Diesel | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 79.5 mm × 95.5 mm | |
| Power output | 96 kW (130 PS) | |
| Torque | 310 Nm @ 1,900 rpm | |
| Fuel system | Bosch VP37 rotary injection pump | |
| Emissions standard | Euro 3 | |
| Compression ratio | 19.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Single fixed-geometry turbo (Garrett or KKK) | |
| Timing system | Belt-driven (requires periodic replacement) | |
| Oil type | VW 505 00 (SAE 5W‑40) | |
| Dry weight | 145 kg |
The fixed-geometry turbo provides strong low-RPM torque ideal for towing and load-carrying but necessitates strict adherence to 15,000 km oil change intervals using VW 505 00 specification to protect the injection pump and turbo bearing. The timing belt must be replaced every 120,000 km or 5 years to prevent catastrophic interference engine failure. The tandem pump is a known weak point; pre-emptive replacement is recommended if symptoms arise. Ultra-low-sulfur diesel (ULSD) is required to prevent injection pump wear.
Oil Specs: Requires VW 505 00 specification (Volkswagen Owner's Manual). ACEA B3/B4 is the minimum equivalent standard.
Emissions: Euro 3 certification applies to all production years (VCA Type Approval #VCA/EMS/5680).
Power Ratings: Measured under DIN 70020 standards. Peak output requires EN 590 diesel fuel (Volkswagen Workshop Manual SSP 233).
Volkswagen Technical Service Bulletins: TSB 2015003/1
Volkswagen Workshop Manuals: SSP 233, SSP 235
Volkswagen ETKA Parts Catalogue
VCA Type Approval Database (VCA/EMS/5680)
The Volkswagen AQD was used across Volkswagen's A4 platform with transverse mounting. This engine shared its core architecture with the ALH and AHU variants but featured unique ECU calibrations and ancillary components for specific model applications. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the cylinder block, just below the fuel injection pump and behind the timing belt cover (Volkswagen SSP 233). The 8th VIN digit typically corresponds to the engine code ('A' for many TDI variants, but verification via the block stamp is definitive). The AQD can be visually identified by its Bosch VP37 rotary injection pump mounted on the left side of the engine and the black plastic intake manifold. Critical differentiation from other 1.9 TDI codes (e.g., ALH, AHU) often requires checking the ECU part number or specific ancillary components like the tandem pump. Service parts, particularly for the fuel system, may vary between model applications and require VIN or engine code verification.
The AQD's primary reliability risk is tandem pump failure, with elevated incidence in high-mileage vehicles. Internal Volkswagen service data indicates this is a frequent cause of workshop visits. Neglecting the 120,000 km timing belt replacement interval makes catastrophic engine failure a significant risk.
Analysis derived from Volkswagen technical bulletins (2000-2005) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN AQD.
Comprehensive technical documentation and regulatory references
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VOLKSWAGEN Official Site
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EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
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VCA Certification Portal
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