Audi A6 Turbo

From the 1.8 T to the 3.0 TDI: which turbo for the Audi A6, by generation and power output?

The answer depends above all on the engine code, not just the engine capacity: on the 2.0 TDI, for example, references differ between 121, 136, 140, 163, 170 and 177 hp, and several codes can share the same quoted power output. The 3.0 TDI follows the same logic, with distinct turbos depending on whether the variant produces 211, 218, 240, 245 or 272 hp, or whether it is the 40 TDI Mild Hybrid unit (code DTPA or DFBA), which takes a specific reference.

Diesel: 2.5 TDI, 2.7 TDI, 3.0 TDI — very different architectures

The 2.5 TDI engines (150 to 180 hp, codes AFB, AKN, AYM, AKE, BDH) are fitted to the C5 and use variable geometry; their turbo is well known for suffering from the gradual fouling of the variable-geometry mechanism, often made worse by infrequent oil changes or degraded oil. The 2.7 TDI (163 and 180 hp) uses a single variable-geometry turbo — not to be confused with the 2.7 T V6 Biturbo petrol (codes APB, BES), which runs two fixed-geometry turbos — the right-hand side of which has its own separate reference in this collection. The 3.0 TDI (codes CDUC, CKVC, CDNB, CDYB, CDYA, CDYC, CRTD, CRTE…) spans several generations of C6, C7 and C8; power output alone is not enough to identify the correct turbo — the model year and engine code are essential.

Petrol: 1.8 T, 1.8 TFSI, 2.0 TFSI — new or reconditioned depending on the version

The 1.8 T 150 and 180 hp engines (codes BAU, BCZ, BDG, BFC, BFB…) are available as a reconditioned turbo; the other petrol engines in this collection — 1.8 TFSI 190 hp (CYPA), 2.0 TFSI from 180 to 252 hp (CAEB, CAED, CAEA, CDNC, CFKA, CPMA, CYMC, CYGA…) — are offered as a new turbo only. Common symptoms on these engines include: whistling under acceleration, blue-grey smoke, a marked loss of power, or the vehicle entering limp mode. Before any replacement, it is essential to identify the root cause: an intake hose gasket failure, fouling of the DPF or EGR circuit, or inadequate lubrication at start-up. Fitting a replacement turbo without addressing the underlying cause will invariably lead to another failure.