I have been having the same issue with my PH04 for the past few years and this has arguably been one of the most frustrating problems I have had to resolve. I purchased a PH04 a on November 2020. The machine was fine for a year. I then started getting this orange light with an exclamation point (see picture attached). After 4 phone calls and one service center visit over a span of 6 months (trust me- this is a different frustrating story), Dyson finally replaced this machine in February 2023. 5 months later, I have the same exact issue. 

I have done everything from reset, purchased new filters, purchased a new water tank, everything. Nothing is resolving the problem. On top of all of this, Dyson is telling me that they cannot cover me under warranty because my warranty doesn’t carry over with the new replacement product they gave me even though it became defective 5 months later.

Any help or advice on how I can fix this would be so appreciated. Thank you!!