T6 aftermarket digital cluster range showing wrong figures

The Problem

After fitting an aftermarket digital instrument cluster, the fuel range displayed wildly incorrect figures and flickered between two different values within seconds of startup. The owner had already tried setting the tank size to 80 L and following a YouTube guide that used VCDS basic settings to change the distance unit, neither of which resolved the issue. The reason VCDS made no difference here is important: VCDS reads and writes coding on the van's OEM CAN-bus modules, but an aftermarket cluster stores its own display settings (tank capacity, units, range calculation) internally. Those values have to be changed in the cluster itself, not through VCDS — so any VCDS basic-settings adjustment will not touch the range figure on this kind of unit.

Solution

Check your van's actual fuel tank size before adjusting any cluster settings — most base-spec T6 Startline vans have a 70 L tank, not the 80 L that is often assumed.
- Confirm this in your vehicle handbook or by checking the label near the fuel filler cap.
Open the settings menu on your specific aftermarket cluster and change the tank capacity from 80 L to 70 L.
- The exact menu path varies between units, so identify the brand and model of your cluster and follow its own instructions (verify the make and model of your cluster before searching for its menu, as layouts differ significantly between suppliers).
- Do not expect VCDS to fix this — as noted above, the tank capacity on an aftermarket cluster lives in the cluster's own menu, which is why the earlier VCDS basic-settings attempt had no effect.
- This single change corrected the displayed range for the owner who resolved the problem.
If the range still jumps between two figures after correcting the tank size, this may point to a firmware bug rather than a settings error.
- Find your current firmware version (usually shown in the cluster's settings or 'About'/'Info' menu) and note it down.
- Contact the cluster supplier directly, quote that firmware version, and ask whether the flickering range is a known issue and whether a patched firmware or rollback is available (verify the firmware version and the supplier's guidance before assuming a regression — do not flash unofficial firmware).