DIAGNOSIS Using non-Dyson filters will cause performance issues and error states. The machine is calibrated for the specific airflow resistance of genuine filters.
FIX You must use the genuine Dyson Purifier HEPA/Carbon Combi Filter (part number 970786-01 for the BP04). Third-party filters often lack the correct seal, carbon weight, or HEPA standard. Install only the specified filter.
IF THAT DIDN'T WORK If you have installed a third-party filter and the machine shows errors or 'Check Filter', you have confirmed the incompatibility. Remove the third-party filter immediately. Install a genuine Dyson filter and reset the filter life counter in the app.
HEADS UP Using unofficial filters will void your machine's warranty. Dyson will not provide support for machines using them. The formaldehyde sensor and auto-mode algorithms rely on the known performance of the genuine filter. A non-genuine filter makes the air quality readings and automation unreliable.