Volkswagen Bora Turbo

On the Bora, the engine code stamped on the block is the only way to determine which turbo to fit

The Bora has twelve distinct engine codes for one and the same 1.9 TDI listed in the catalogue — and each code corresponds to a different part. ARL (150 hp), ASZ (130 hp), AJM and AUY (115 hp), AGR and ALH (90 hp), ASV, ATD, AXR and BVK (90 to 115 hp depending on version): none of these parts is interchangeable with another. Reading the power output on the registration document is not enough — two 115 hp Boras carry different codes and require different turbos.

Diesel: variable geometry on the higher-output codes, fixed geometry on the early 90 hp units

The AGR and ALH codes equip the early 90 hp versions with fixed-geometry turbos and a wastegate. The AJM and AUY codes (115 hp) move to variable geometry. The ARL 150 hp uses a distinct variable-geometry turbo with larger vanes and a larger-section CHRA. The ASZ 130 hp has its own reference. On these diesel engines, common failures stem from inadequate lubrication — degraded oil or leaving the engine idling too long before switching off — or from a blocked intake circuit. Before any replacement, checking the condition of the oil circuit, the filter and the turbo feed pipe is essential to avoid repeating the same damage.

Petrol 1.8 T 180 hp: codes ARZ and AUQ, reconditioned turbo on an exchange basis

The 1.8 T 180 hp — codes ARZ and AUQ — is the only petrol engine on the Bora covered here. Unlike the diesel turbos offered new, the 1.8 T 180 hp unit is available in reconditioned form. Typical failure symptoms on this engine include a whistling noise under load, blue smoke from the exhaust or a loss of boost pressure. On this engine, bearing clearances and the condition of the CHRA are the first points to check during diagnosis.