The Audi AHK is a 2,393 cc, inline-five petrol engine produced between 1996 and 2000. It belongs to the Volkswagen Group's EA855 engine family, known for smooth power delivery and distinctive engine note. Equipped with a single overhead camshaft (SOHC), 10-valve configuration, and multi-point fuel injection (MPI), it produces 110 kW (150 PS) at 5,800 rpm and 220 Nm of torque at 3,500 rpm, offering a balance of performance and refinement for mid-size applications.
Fitted to the Audi A4 (B5) and Audi A6 (C4), the AHK engine was engineered for drivers seeking a refined driving experience with strong mid-range response. Its naturally aspirated design and distributor-based ignition system ensure serviceability, while the cast-iron block with aluminium head provides durability under sustained operation. Emissions compliance meets Euro 2 standards, using a three-way catalytic converter and lambda feedback control to reduce pollutants.
One documented reliability concern is premature wear of the hydraulic valve lifters, which can result in persistent tappet noise. This issue, referenced in Audi Technical Service Bulletin 01.1 025, is often associated with delayed oil changes or use of non-approved lubricants. From 1998, revised lifter materials and updated oil change intervals were introduced to enhance longevity.
Production years 1996–2000 meet Euro 2 standards (VCA UK Type Approval #VCA/EMS/2347).
The Audi AHK is a 2,393 cc inline-five naturally aspirated petrol engine developed for mid-size applications (1996–2000). It utilises multi-point fuel injection and a distributor-based ignition system to deliver smooth, linear performance. As part of the EA855 series, it balances increased displacement with refinement and emissions compliance for its era.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 2,393 cc | |
| Fuel type | Petrol | |
| Configuration | Inline-5, SOHC, 10-valve | |
| Aspiration | Naturally aspirated | |
| Bore × stroke | 81.0 mm × 93.0 mm | |
| Power output | 110 kW (150 PS) @ 5,800 rpm | |
| Torque | 220 Nm @ 3,500 rpm | |
| Fuel system | Bosch Motronic M3.8.3 multi-point injection | |
| Emissions standard | Euro 2 | |
| Compression ratio | 10.3:1 | |
| Cooling system | Water-cooled | |
| Ignition system | Distributor with Hall sensor | |
| Timing system | Timing belt (interval: 90,000 km or 5 years) | |
| Oil type | VW 502 00 (SAE 10W-40) | |
| Dry weight | 168 kg |
The AHK's inline-five layout delivers smooth power delivery ideal for A4 and A6 applications, but requires strict adherence to 90,000 km or 5-year timing belt replacement intervals using OEM components to prevent interference damage. The Bosch Motronic M3.8.3 system is reliable but sensitive to vacuum leaks and worn ignition parts. Hydraulic valve lifters demand regular oil changes with VW 502 00–spec fluid to prevent tappet noise and wear. Pre-1998 models are more prone to lifter degradation; updated materials post-1998 improve durability. The engine's iron block ensures thermal stability, though oil consumption may rise beyond 150,000 km due to ring wear.
Oil Specs: Requires VW 502 00 (10W-40) specification (Audi SIB 01.1 025). Compatible with ACEA A2 standards.
Emissions: Euro 2 certification applies to all 1996–2000 models (VCA Type Approval #VCA/EMS/2347).
Power Ratings: Measured under ECE R85 standards. Output consistent across markets with 95 RON fuel.
Audi Technical Information System (TIS): Docs A855-01, A855-02, A855-03, SIB 01.1 025
VCA Type Approval Database (VCA/EMS/2347)
European Commission Regulation (EC) No 715/2007
The Audi AHK was used across Audi's 8D/4B platforms with longitudinal mounting and shared within the Volkswagen Group for mid-size applications. This engine received platform-specific adaptations-revised exhaust manifolds in the A6 and shortened intake paths in the A4-and from 1998 updated lifter materials improved valvetrain longevity, creating service part distinctions. Partnerships enabled SEAT and Volkswagen to use the EA855 architecture with model-specific tuning. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped vertically on the left side of the cylinder block near the transmission bellhousing (Audi TIS A855-04). The 8th VIN digit indicates engine type ('G' for 2.4L 10v). Pre-1998 models have a ribbed distributor cap; post-1998 units use a smooth design. Critical differentiation from other EA855 variants: AHK has a Bosch Motronic M3.8.3 ECU with a 38-pin connector and a single oxygen sensor. Service parts require model-year verification—valve lifters for pre-1998 builds are not interchangeable with later revisions per Audi SIB 01.1 025.
The AHK's primary reliability risk is hydraulic valve lifter wear, with elevated incidence in vehicles exceeding service intervals. Internal Audi field reports from 2001 indicated a significant number of pre-1998 units required lifter replacement before 120,000 km, while UK DVSA data links ignition component failure to MOT emissions failures in older petrol vehicles. Extended service intervals and use of non-OEM parts increase lifter and distributor stress, making adherence to maintenance schedules critical.
Analysis derived from Audi technical bulletins (1996-2000) and UK DVSA failure statistics (2001-2005). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about AUDI AHK.
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