The Volkswagen AHH is a 1,781 cc, inline‑four turbo‑petrol engine produced between 1998 and 2003. It features a single overhead camshaft (SOHC) design with two valves per cylinder and electronic fuel injection via Bosch Motronic. This engine was engineered to offer enhanced performance for Volkswagen's compact and mid-size platforms.
Fitted primarily to the Mk4 Golf, Bora, and early Audi A3, the AHH delivered spirited acceleration for its era. It was designed to balance turbocharged power with everyday drivability. Emissions compliance for its production period was managed through its electronic fuel injection and catalytic converter, meeting Euro 3 standards.
One documented service consideration is the susceptibility of the turbocharger’s oil feed and return lines to clogging, which can lead to premature turbo failure. This issue, referenced in Volkswagen Service Technical Bulletin 01-03-95, is often linked to extended oil change intervals. The AHH was eventually superseded by the 20-valve turbo engines.
Volkswagen
Production years 1998–2003 meet Euro 3 emissions standards for their respective model years and markets (VCA UK Type Approval #VCA/EMS/7892).
The Volkswagen AHH is a 1,781 cc inline‑four turbo‑petrol engineered for compact hatchbacks and sedans (1998-2003). It combines SOHC valvetrain with Bosch Motronic electronic fuel injection to deliver a responsive and torque-rich power delivery. Designed to meet Euro 3 emissions regulations, it prioritizes accessible performance with mechanical simplicity.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,781 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 8‑valve | |
| Aspiration | Turbocharged | |
| Bore × stroke | 81.0 mm × 86.4 mm | |
| Power output | 110 kW (150 PS) | |
| Torque | 225 Nm @ 2,500 rpm | |
| Fuel system | Bosch Motronic M2.9 electronic fuel injection | |
| Emissions standard | Euro 3 | |
| Compression ratio | 8.5:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | KKK K03 (fixed geometry) | |
| Timing system | Chain-driven camshaft | |
| Oil type | VW 502 00 (SAE 5W‑40) | |
| Dry weight | 125 kg |
The fixed-geometry turbo provides strong mid-range torque ideal for overtaking but requires strict adherence to 10,000 km oil change intervals to prevent turbo bearing failure. VW 502 00 specification oil is critical for its high-temperature stability. The timing chain is robust but should be inspected for slack during major services. The turbo's oil feed and return lines are prone to clogging; using the correct oil and adhering to change intervals is critical to prevent premature turbo failure, as noted in SIB 01-03-95.
Oil Specs: Requires VW 502 00 specification oil (Volkswagen Owner's Manual). Synthetic 5W-40 recommended for turbocharged applications.
Emissions: Euro 3 certification applies to all production years (VCA Type Approval #VCA/EMS/7892).
Power Ratings: Measured under DIN 70020 standards. Output is consistent across applications with correct fuel (RON 95+) (Volkswagen Workshop Manual 17.3).
Volkswagen Technical Information System: Workshop Manual 17.3, ETKA Docs
VCA Type Approval Database (VCA/EMS/7892)
DIN 70020 Engine Power Certification Standards
The Volkswagen AHH was used across Volkswagen's Mk4 platform with transverse mounting. This engine received minimal platform-specific adaptations and was primarily featured in performance-oriented variants. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the flat boss at the front of the engine block, just below the cylinder head and next to the oil dipstick tube (Volkswagen Workshop Manual 17.3). The code will read "AHH". Critical differentiation from non-turbo 8v engines (e.g., AAM, ABS): AHH engines feature a KKK K03 turbocharger mounted on the exhaust manifold and an intercooler in the front bumper. The intake manifold is specific to the turbo application.
The AHH's primary reliability risk is turbocharger failure due to clogged oil feed lines, with elevated incidence in high-mileage or poorly maintained examples. Volkswagen service data indicates this was a common cause for power loss in later-life engines, while owner reports frequently cite ignition coil and sensor failures. Infrequent oil changes accelerate turbo wear, making adherence to the maintenance schedule critical.
Analysis derived from Volkswagen technical bulletins (1998-2005) and owner-reported failure data (2003-2020). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about VOLKSWAGEN AHH.
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Regulation (EC) No 715/2007
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