Heat pump tumble dryer filter light staying on after cleaning (all brands)

Heat pump tumble dryers have more filters than a standard vented or basic condenser dryer, and a filter warning light staying on after cleaning “the” filter is very often because a second, easily-missed filter or the heat exchanger itself still needs attention.

What to check first

1. Clean the standard lint filter (usually inside the door) as normal.
2. Check for a second, often larger fluff filter — many heat pump dryers have one behind a front or lower panel, separate from the door filter, and this is the one most commonly forgotten.
3. Clean the heat exchanger unit itself (check your manual for its exact location, often accessed via a lower front panel) — this collects fine dust and lint over time even when both filters are clean, and manufacturers typically recommend cleaning it every few months.
4. Once cleaned, some models need a specific reset action (holding a button, or simply running a cycle) before the warning light clears — check your manual if the light doesn’t clear immediately after cleaning.

When to call an engineer

If you’ve cleaned the door filter, the secondary fluff filter, and the heat exchanger, and followed any reset steps, but the light still won’t clear, the filter sensor itself may have a fault — worth a professional check.