Description

This is a professional-grade reconditioned Garrett GT15 turbocharger, specifically rebuilt for the Audi A4 1.9 TDI (1995-2001) models equipped with the AFN or AHU diesel engines. At Gap Turbos in Birmingham, we restore these units to original manufacturer specifications to ensure reliable boost pressure, optimal fuel economy, and long-term durability.

The 1.9 TDI engine is legendary for its longevity, but the turbocharger operates under extreme thermal and mechanical stress. This unit, carrying OEM part number 28145702 (Garrett alternative 454097-5002S), features a wastegate-regulated GT15 design. Common failure modes on these older TDI engines include carbon build-up around the internal components, wastegate actuator diaphragm failure, and journal bearing wear caused by oil contamination or restricted oil feed pipes. Left unchecked, bearing wear can lead to housing contact and catastrophic shaft failure.

What this turbocharger fits

This turbocharger is a direct replacement for the Audi A4 B5 1.9 TDI diesel models manufactured between 1995 and 2001. It is compatible with both the 110 HP AFN engine and the 90 HP AHU engine variants. Please cross-reference your existing turbo housing numbers with OEM reference 28145702 or Garrett part number 454097-5002S to confirm compatibility before ordering.

At our Birmingham workshop, our reconditioning process is exhaustive. We completely strip the unit, discard all worn internal components, and clean the housings using specialist ultrasonic equipment. We install a brand-new bearing assembly, high-temperature seals, and a new wastegate actuator. The core is then balanced on our high-speed VSR rig to tolerances exceeding OEM standards. We offer this unit on a service exchange basis, or we can recondition your original unit. We also provide a professional fitting service at our workshop, which includes a comprehensive engine oil flush and feed pipe replacement. Every rebuild undergoes rigorous multi-stage testing. Balancing is critical for the GT15 frame, as even minor imbalances at high RPMs will cause premature bearing failure. When you choose Gap Turbos, you are benefiting from over three decades of specialist turbocharger engineering experience.

Contact Gap Turbos today for a competitive quote; all our reconditioned turbochargers come backed by a comprehensive 12-month warranty.

Specifications

Vehicle fitment

• Audi A4 TDI 1.9

Common faults & troubleshooting

[‘Blue exhaust smoke under acceleration: Worn dynamic shaft seals inside the turbocharger are allowing engine oil to leak into the intake or exhaust tracts; replace the turbo unit.’, ‘Complete loss of power (limp mode) with boost deviation fault codes: A seized or sticking wastegate actuator mechanism is preventing boost regulation; check the actuator vacuum line or replace the unit.’, ‘High-pitched whistling or whining noise under load: Damage to the compressor wheel blades from foreign object debris or excessive shaft play causing the wheel to contact the housing; immediate replacement is required.’, ‘Lack of low-end power and delayed boost response: Excessive carbon build-up inside the turbine housing restricting gas flow or a leaking actuator diaphragm; the turbo requires professional cleaning or rebuilding.’]

Fitting notes for this unit

[‘Always replace the oil feed pipe (feed line) with a brand-new OE item; never attempt to clean or reuse the old pipe as carbon deposits will restrict oil flow to the new bearings.’, ‘Prior to installation, prime the turbocharger by pouring fresh, clean engine oil into the oil inlet port and rotating the compressor wheel by hand to ensure initial lubrication.’, “Ensure all exhaust manifold and downpipe mating surfaces are perfectly clean, and always use new high-temperature gaskets and copper-flanged nuts torqued to the manufacturer’s specification.”, ‘Perform a complete engine oil and filter change using the correct VW 505.00 spec oil before starting the engine with the new turbocharger installed.’, “Disable the engine’s fuel supply or crank angle sensor and crank the engine in 10-second bursts until the oil pressure warning light goes out, ensuring oil pressure is fully established before the engine starts.”]

Alternative part numbers

This turbo is also referenced by:

• 454097-5002s — GT15 Turbocharger OE 454097-5002s (Audi A4 TDI 1.9, AFN/AHU, 110hp)

Frequently asked questions