Audi A4 Turbo

Audi A4 Turbo: from the 1.9 TD 75 hp of the early B5 to the mild-hybrid and bi-turbo RS4 units — a proliferation of references that makes correct identification critical

On the Audi A4, the stated engine capacity alone is not enough to identify the correct turbo. A 2.0 TDI can produce 120, 126, 136, 140, 143, 150, 163, 170, 177, 190 or 204 hp depending on the generation and engine code, and each of those power outputs may correspond to a different turbo reference. The same applies to petrol engines: the 2.0 TFSI covers codes ranging from BGB to DDWA, with different turbos depending on the variant. The engine code stamped on the block — not the engine capacity or the marketed power output — is the only reliable starting point for identifying the correct reference.

Diesel: from the 1.9 TDI to the 3.0 TDI six-cylinder — families with no interchangeability

The first A4 B5 diesel models started with the 1.9 TD code AAZ (75 hp), followed by the 1.9 TDI range covering codes such as 1Z, AFN, AHU, AJM, ATJ and BKE depending on power output and year. The move to 2.0 TDI units introduced a new family: codes BLB, BNA, BRE and BVF for the 121–140 hp versions, then CAGA, CAGB, CAGC, CJCA, CJCB, CMEA, CMFA, CSUA and CSUB for the subsequent generations producing 120–150 hp — two distinct code groups that do not share the same turbo. The 170 hp versions carry codes BRA, BRD, BVA or CAHA depending on the generation. The 2.5 TDI V6 (codes AFB, AKE, AKN, AYM, BCZ and others) and the 2.7 TDI (BPP, BSG, CANB, CAMA, CGKA) each have their own references. The 3.0 TDI is split into three code families according to power output and generation: CAPA, CCWA, CPNB for the 211–240 hp versions; CRTC, CSWB, CZVA for the 218–272 hp versions; DCPE, DHXA, DPXA for the 231–286 hp versions. The 2.0 TDI 204 hp mild-hybrid (codes DFBA, DTP, DTPA) uses a different turbo from all previous 2.0 TDI units.

Petrol and RS4: 1.8 T, TFSI and bi-turbo — unrelated geometries and configurations

The 1.8 T (codes AEB, AMG, ANB, APU, ATW, AWM, AWT and others) is mechanically unrelated to the TFSI units that succeeded it. The 1.4 TFSI 150 hp (code CVNA) is a standalone engine with its own turbo reference. The RS4 B9 is fitted with a 2.9 TFSI bi-turbo 450 hp (code DECA): two fixed-geometry turbos arranged in a twin-turbo configuration — an architecture that bears no comparison with the turbos used on four-cylinder TFSI engines. The turbos available in this collection are new for the vast majority of engine variants; only certain 2.0 TDI (120–143 hp) and the 1.8 T also have a reconditioned reference available. Before any replacement is carried out, the root cause of the failure — insufficient lubrication, degraded oil, contamination, foreign object ingestion — must be identified and rectified; failing to do so will expose the new part to the same conditions.