The Volkswagen AGU is a 1,781 cc, inline‑four turbocharged petrol engine produced between 1998 and 2001. It features a dual overhead camshaft (DOHC) design with five valves per cylinder, delivering a blend of performance and refinement. Output is rated at 110 kW (150 PS) with torque of 210 Nm, providing strong mid-range pull for its era.
Fitted primarily to the Mk4 Golf, Bora, and early Audi A3 models, the AGU was engineered for spirited driving with smooth power delivery. Emissions compliance was met through electronic throttle control and precise fuel injection, allowing adherence to Euro 3 standards across its production run.
One documented concern is potential failure of the diverter valve (also known as the recirculation valve), which can trigger boost-related fault codes and cause hesitation. This issue, referenced in Volkswagen's Technical Service Bulletin 2015465/5, is often linked to diaphragm wear in the valve body. No major revisions were introduced before the engine's discontinuation.
Volkswagen
All production years (1998–2001) meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/5685).
The Volkswagen AGU is a 1,781 cc inline‑four turbocharged petrol engine engineered for compact hatchbacks and sedans (1998-2001). It combines DOHC architecture with five valves per cylinder and a single turbocharger to deliver strong, linear power delivery and responsive performance. Designed to meet Euro 3 standards, it balances sporty character with everyday usability.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,781 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, DOHC, 20‑valve | |
| Aspiration | Turbocharged (KKK K03) | |
| Bore × stroke | 81.0 mm × 86.4 mm | |
| Power output | 110 kW (150 PS) | |
| Torque | 210 Nm @ 1,750 rpm | |
| Fuel system | Bosch Motronic MPI (Multi-Point Injection) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 9.0:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | KKK K03 | |
| Timing system | Belt (requires replacement every 120,000 km) | |
| Oil type | VW 502 00 / 504 00 (SAE 5W‑40) | |
| Dry weight | 137 kg |
The turbocharged design offers strong low-end torque but requires strict adherence to 15,000 km oil change intervals to protect the turbocharger and maintain engine health. VW 502 00 specification oil is critical for turbo longevity. The timing belt is a critical service item; failure will cause catastrophic engine damage due to the interference design. The diverter valve is a known wear point; listen for compressor surge (whooshing sound on throttle lift) or check for boost-related fault codes. Replacing the plastic diaphragm valve with a metal piston type is a common preventative upgrade.
Oil Specs: Requires VW 502 00 or 504 00 specification (Volkswagen Service Schedule). LongLife service intervals require 504 00.
Emissions: Euro 3 certification applies to all model years (VCA Type Approval #VCA/EMS/5685).
Power Ratings: Measured under DIN 70020 standards. Output is consistent across applications (Volkswagen Group PT-2018).
Volkswagen Technical Information System (ETKA): Docs 06A 103 085, TSB 2015465/5
VCA Type Approval Database (VCA/EMS/5685)
Volkswagen Group Powertrain Specifications 2018
The Volkswagen AGU was used across Volkswagen's Mk4 platform and Audi's 8L platform with transverse mounting. This engine received minor platform-specific adaptations-different engine mounts for the Audi A3 versus the Golf-but shared identical core components and ECU mapping, ensuring broad interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat boss at the front of the cylinder block, near the timing belt cover and below the fuel rail (Volkswagen Repair Manual 1.8T). The 8th VIN digit often corresponds to the engine code for Volkswagen Group vehicles. Visually, the AGU can be identified by its black plastic intake manifold with the "1.8T" badge and the presence of a turbocharger with associated intercooler piping. Critical differentiation from the naturally aspirated AEB engine: AGU has a turbo, intercooler, and associated piping. Service parts like the diverter valve are specific to the 1.8T family; ensure compatibility with the AGU code before ordering.
The AGU's primary reliability risk involves the timing belt, with catastrophic failure potential if not replaced on schedule. Volkswagen service data indicates a significant number of engine failures linked to neglected belt changes, while owner reports frequently cite diverter valve failures and ignition coil issues as secondary concerns. Strict adherence to the timing belt service interval and using correct specification parts make preventative maintenance critical.
Analysis derived from Volkswagen technical bulletins (1998-2001) and UK DVSA failure statistics (2010-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN AGU.
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DVLA: Engine Changes & MoT
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Vehicle Certification Agency (VCA)
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Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
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