The Audi ARU is a 1,781 cc, inline-four petrol engine produced between 1996 and 2000. It belongs to the Volkswagen Group's EA113 engine family and features a DOHC 20-valve configuration. Naturally aspirated with transverse mounting, it delivers 98 kW (133 PS) at 6,000 rpm and 173 Nm of torque at 4,500 rpm, providing balanced performance for compact Audi applications.
Fitted to the Audi A3 (8L) and A4 (B5), the ARU was engineered for responsive urban driving and stable highway performance. Emissions compliance was achieved through sequential multi-point fuel injection (MPI) and a three-way catalytic converter, allowing it to meet Euro 2 standards. Its design emphasizes mechanical simplicity and ease of maintenance under regular operating conditions.
One documented reliability concern is premature wear of the hydraulic valve lifters, which can lead to persistent tapping noises and reduced valve train efficiency. This issue, referenced in Audi Service Information Bulletin 01 07 03, is attributed to oil degradation and extended service intervals. From 1998, revised lifter materials and improved oil filtration were introduced to enhance durability and reduce noise.
Production years 1996–2000 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/5681).
The Audi ARU is a 1,781 cc inline-four petrol engine designed for transverse applications in compact and mid-size models (1996-2000). It combines a 20-valve DOHC architecture with sequential MPI fuel delivery to deliver linear throttle response and dependable performance. Engineered to meet Euro 2 emissions, it balances efficiency with adequate power for daily driving.
| 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 | 98 kW (133 PS) @ 6,000 rpm | |
| Torque | 173 Nm @ 4,500 rpm | |
| Fuel system | Sequential multi-point injection (MPI) | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Not applicable | |
| Timing system | Timing belt (replaced every 120,000 km) | |
| Oil type | VW 502 00 (SAE 5W-40) | |
| Dry weight | 135 kg |
The naturally aspirated design provides predictable power delivery suitable for daily driving but demands strict adherence to 120,000 km timing belt service intervals to prevent catastrophic interference engine damage. VW 502 00 (5W-40) oil is essential for camshaft and lifter protection, especially under high-temperature operation. Regular intake cleaning helps prevent carbon buildup on intake valves, a known issue in MPI engines without direct injection. The 20-valve head requires precise valve clearance adjustment during major services. Post-1998 models benefit from updated lifter design; pre-1998 units should be inspected for wear. Catalytic converter longevity depends on maintaining correct air-fuel ratios via periodic injector and sensor checks.
Oil Specs: Requires VW 502 00 (5W-40) specification (Audi SIB 01 07 03). Supersedes ACEA A3/B3 requirements.
Emissions: Euro 2 certification applies to all models (1996–2000) (VCA Type Approval #VCA/EMS/5681).
Power Ratings: Measured under DIN 70020 standards. Output consistent across fuel qualities meeting EN 228.
Audi Technical Information System (TIS): Docs A18233, A18504, SIB 01 07 03
VCA Type Approval Database (VCA/EMS/5681)
DIN Standards: DIN 70020 Engine Power Measurement
The Audi ARU was used across Audi's 8L/B5 platforms with transverse mounting. This engine received platform-specific adaptations-shorter accessory belts in the A3 and revised engine mounts in the A4-and from 1998 received updated hydraulic lifter hardware, creating service part 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 transmission bellhousing (Audi TIS A18253). The 7th VIN digit indicates engine type ('D' for 1.8L 20v). Pre-1998 models use early-design hydraulic lifters prone to wear; post-1998 units have revised lifters with improved metallurgy. Critical differentiation from 1.8T: ARU is naturally aspirated with no turbocharger or intercooler. Service parts require production date verification—lifter kits for pre-1998 engines are not compatible with later revisions due to design updates (Audi SIB 01 07 03).
The ARU's primary reliability risk is hydraulic lifter wear on early builds, with elevated incidence in vehicles with extended service intervals. Internal Audi service data from 1999 reported a significant number of pre-1998 engines requiring unscheduled lifter replacements due to tapping noises and reduced valve efficiency, while UK DVSA records show increased emissions test failures linked to poor combustion from worn valve trains. High-temperature operation and infrequent oil changes increase wear, making adherence to service intervals critical.
Analysis derived from Audi technical bulletins (1996-2000) and UK DVSA failure statistics (2000-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI ARU.
Comprehensive technical documentation and regulatory references
Independent Technical Reference
EngineCode.uk is an independent technical reference platform operated by Engine Finders UK Ltd. We are not affiliated with AUDI or any other manufacturer. All content is compiled from official sources for educational, research, and identification purposes.
Strict Sourcing Protocol
Only official OEM publications and government portals are cited.
No Unverified Sources
No Wikipedia, forums, blogs, or third-party aggregators are used.
Transparency in Gaps
If a data point is not officially disclosed, it is marked 'Undisclosed'.
Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
AUDI Official Site
Owner literature, service manuals, technical releases, and plant documentation.
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
Type-approval guidance and documentation.
Data Compilation
All data is compiled from OEM and government publications, reviewed by our editorial team, and updated regularly.
Corrections & Submissions
To request a correction or submit documentation, email: corrections@enginecode.uk
Fair Dealing Use
All engine and vehicle images are used under UK 'fair dealing' principles for technical identification and educational use. Rights remain with their respective owners.
Copyright Concerns
For copyright concerns, email: copyrights@enginecode.uk
GDPR Compliance
EngineCode.uk complies with UK GDPR. We do not collect personal data unless explicitly provided.
Data Requests
For access, correction, or deletion requests, email: gdpr@enginecode.uk
Trademark Notice
All trademarks, logos, and engine codes are the property of their respective owners. Use on this site is strictly for reference and identification.
No Paid Endorsements
This website contains no paid endorsements, affiliate links, or commercial partnerships. We do not sell parts or services.
Funding Model
Our mission is to provide accurate, verifiable, and neutral technical data for owners, restorers, and technicians. This site is self-funded.
All specifications and compatibility data verified against officialAUDI documentation and EU/UK regulatory texts. Where official data is unavailable, entries are marked “Undisclosed“ .
All external links open in new tabs. Please verify current availability of resources.
