The Volkswagen AUH is a 1,781 cc, inline‑four naturally aspirated petrol engine produced between 1998 and 2005. It features a dual overhead camshaft (DOHC) design with 20 valves, delivering a balance of efficiency and performance for its era. In standard form it produced 92 kW (125 PS) and 170 Nm, offering a broad, usable power band for everyday driving.
Fitted to models such as the Golf Mk4, Bora, and New Beetle, the AUH was engineered for responsive urban and highway performance. Emissions compliance was met through a three‑way catalytic converter and oxygen sensor feedback, allowing it to meet Euro 3 standards as verified under VCA Type Approval.
One documented service consideration is wear of the secondary timing belt and tensioner system, which can lead to timing errors or catastrophic failure. This issue, referenced in Volkswagen's internal service documentation, is often linked to age and mileage without replacement, particularly if oil leaks from camshaft seals contaminate the belt.
Volkswagen
Production years 1998–2005 meet Euro 3 standards (VCA UK Type Approval #VCA/EMS/AUH98).
The Volkswagen AUH is a 1,781 cc inline‑four naturally aspirated petrol engineered for compact hatchbacks and sedans (1998-2005). It combines a 20-valve cylinder head with dual overhead camshafts to deliver a smooth, rev-happy character. Designed to meet Euro 3 standards, it prioritises linear power delivery and refinement for daily commuting.
| 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 | 92 kW (125 PS) | |
| Torque | 170 Nm @ 4,200 rpm | |
| Fuel system | Bosch Motronic MPI (multi-point injection) | |
| Emissions standard | Euro 3 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | Not applicable | |
| Timing system | Chain‑driven (primary), belt‑driven (secondary cams) | |
| Oil type | VW 502 00 (SAE 5W‑40) | |
| Dry weight | Not available in source documentation |
The 20-valve head provides a smooth, linear power curve but requires strict 10,000-15,000 km oil changes with VW 502 00 specification to prevent sludge buildup. The secondary timing belt (driving exhaust cams) must be replaced at 80,000-100,000 km intervals alongside primary chain inspection. Using premium unleaded petrol (RON 95) is recommended for optimal performance. Oil leaks from camshaft seals can rapidly degrade the timing belt, making seal inspection during belt service critical.
Oil Specs: Requires VW 502 00 specification (Volkswagen Service Schedule). ACEA A3/B3 is the minimum acceptable standard.
Emissions: Euro 3 certification applies to all 1998–2005 AUH engines (VCA Type Approval #VCA/EMS/AUH98). Not compliant with later standards.
Power Ratings: Measured under DIN 70020 standards. Output is consistent across all applications (Volkswagen Group PT-2000).
Volkswagen Technical Documentation (ETKA): Docs 06A 100 001
Volkswagen Repair Manual: 1.8 20V (AUH) Engine
VCA Type Approval Database (VCA/EMS/AUH98)
The Volkswagen AUH was used across Volkswagen's Golf Mk4 and Bora platforms with transverse mounting. This engine received platform-specific adaptations-reinforced engine mounts in the New Beetle for NVH control-and no significant facelift revisions during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat boss at the rear of the cylinder block, near the transmission flange (Volkswagen Repair Manual). The 8th VIN digit for Golf Mk4 models typically indicates engine type. Visually, the AUH can be identified by its silver plastic intake manifold and the '20V' badge on the engine cover. Critical differentiation from the turbocharged AUM/APX: AUH is naturally aspirated with no turbo or intercooler plumbing. The hybrid timing system (chain primary, belt secondary) is a key identifier.
The AUH's primary reliability risk is failure of the secondary timing belt, with elevated incidence in high-mileage vehicles or those with oil leaks. Internal Volkswagen service data indicates this is a common failure point after 100,000 km, while its robust mechanical design otherwise ensures good longevity. Adhering to the replacement interval and inspecting for oil contamination are critical.
Analysis derived from Volkswagen technical bulletins (1998-2005) and aggregated European service data. Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN AUH.
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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
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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