Question 1

can i use third party filters in the dyson bp04? the official ones are so expensive.

Accepted Answer

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.

Question 2

dyson bp04 display says 'error 5-8' and won't start. what does that mean and how do i fix it?

Accepted Answer

DIAGNOSIS Error 5-8 indicates a communication fault between the main PCB and the display/control panel. FIX Perform a hard reset. Unplug the machine from the wall outlet. Wait for 60 seconds. While unplugged, press and hold the power button on the machine for 20 seconds to discharge any residual power. Plug the machine back in and press the power button to restart. IF THAT DIDN'T WORK The error persists. This requires a deeper reset. With the machine unplugged, remove the main HEPA/carbon filter. Wait 30 seconds. Reinstall the filter, ensuring it clicks into the correct position. Plug the machine back in. The error should clear if it was a sensor glitch. HEADS UP If Error 5-8 returns after these steps, it indicates a likely hardware failure. Continued use is not advised. You must contact Dyson Support directly. Have your machine's serial number ready. The unit may require a PCB replacement.

Question 3

my bp04 turns off by itself overnight even though i didn't set a timer. it's plugged in securely.

Accepted Answer

DIAGNOSIS The machine is likely entering Auto+ mode and, due to low pollutant readings, reducing speed to a near-off state (Fan Speed 1), which is very quiet. FIX Check the current mode. On the display or in the app, ensure it is not set to 'Auto'. If it is, switch it to a manual fan speed (2-10). In Auto mode, if the sensors detect clean air for a prolonged period, the fan slows to its minimum setting, which can be inaudible. IF THAT DIDN'T WORK The Night Mode schedule may be active. In the Dyson Link app, go to the schedule tab and check for any programmed 'Night Mode' periods. Night Mode sets the fan to a very low, quiet speed (Speed 4 or lower) and dims the display, which can be mistaken for being off. HEADS UP There is no automatic shut-off feature outside of a programmed timer. The display will always show a standby light unless fully unplugged. If the unit is truly powering down completely, there is a potential internal fault.

Question 4

how do i clean the actual fan inside the dyson bp04? it's dusty and the manual says not to take it apart.

Accepted Answer

DIAGNOSIS Dust has accumulated on the sealed main bladewheel, which is not designed for user cleaning. This can happen over years of use. FIX You cannot directly clean the sealed bladewheel. Use the machine's built-in cleaning function. Power the unit on. Press and hold the 'Oscillation' button and the 'Night Mode' button simultaneously for 10 seconds. All icons will illuminate. The fan will run at high speed for two minutes to dislodge dust from the internal mechanism. Perform this monthly. IF THAT DIDN'T WORK For external dust, clean the intake grilles at the base with a soft, dry brush or a vacuum cleaner hose attachment. Ensure the pre-filter in the main filter assembly is not clogged—replace the main filter if it is old. HEADS UP Do not attempt to open the main body or remove screws. This will void your warranty and can damage the sealed system. If internal dust buildup is severe and affecting performance, contact Dyson for a professional service check.

Question 5

the formaldehyde reading on my bp04 is always high even in a clean room, is the sensor faulty?

Accepted Answer

DIAGNOSIS The solid-state formaldehyde sensor is likely being triggered by other volatile organic compounds (VOCs), not necessarily formaldehyde. It is a broad VOC indicator. FIX Manually activate the 'Deep Clean' cycle. On the machine or in the app, select the Deep Clean mode. It runs the fan at maximum for up to 30 minutes. This clears the sensor chamber of accumulated compounds that can cause false high readings. After the cycle, check the reading again in a ventilated room. IF THAT DIDN'T WORK Common household items emit VOCs. Remove potential sources from the room: aerosol sprays, strong cleaning chemicals, nail polish remover, new furniture, or certain candles. Run the purifier with these removed for 24 hours. HEADS UP The formaldehyde number on the display is an estimate, not a laboratory-grade measurement. It is sensitive to alcohols and esters found in many products. A consistently high reading in an empty room may require a sensor reset via Dyson Support.

Question 6

dyson bp04 won't connect to wifi, it just flashes the wifi icon and fails. my other devices connect fine.

Accepted Answer

DIAGNOSIS The machine is failing to join your wireless network during the app setup process. FIX This is a multi-cause problem. Follow this checklist. 1. Ensure your phone's Bluetooth is on and you are using the Dyson Link app. 2. Your WiFi network must be a 2.4GHz band. The BP04 does not connect to 5GHz networks. 3. Temporarily disable your mobile data during setup to force the app through WiFi. 4. Move the purifier and your phone closer to the router. 5. Perform a hard reset on the purifier by holding the power button on the machine for 10 seconds until it restarts, then retry. IF THAT DIDN'T WORK Some network security settings block the connection. Try creating a guest network on your router (2.4GHz) with a simpler password (letters and numbers only) and connect the Dyson to that network first. HEADS UP The initial setup requires both Bluetooth (for pairing phone to machine) and WiFi. The machine cannot connect to enterprise networks with splash pages (like universities or some apartments).

Question 7

why is my dyson purifier making a loud rattling noise on the highest fan speed? it's only a few months old.

Accepted Answer

DIAGNOSIS A foreign object is likely lodged in the fan assembly or the loop amplifier (the ring on top). This is common with high-speed airflow. FIX Power off and unplug the machine. Remove the loop amplifier by twisting it counter-clockwise and lifting it off. Visually inspect the main fan bladewheel for debris like hair, dust bunnies, or small objects. Use a flashlight to look inside the base. Remove any debris carefully. IF THAT DIDN'T WORK The rattling could be a loose component. Check that the filter is installed correctly and seated flush. A misaligned filter can cause turbulence and noise. Also ensure the loop amplifier is securely reattached by twisting clockwise until it clicks. HEADS UP Never insert tools or fingers into the fan bladewheel while the unit is plugged in. The fan can spin freely and cause injury. Regular cleaning of the loop amplifier and intake grilles prevents this.

Question 8

my dyson bp04 says filter life 0% but i just replaced them, did i install them wrong or is it broken?

Accepted Answer

DIAGNOSIS The machine is not recognizing the new filter. The filter life counter must be manually reset after a filter change. FIX Reset the filter life counter using the Dyson Link app. Open the app, select your machine, go to the filter section, and select 'Reset Filter Life'. Confirm the reset. The percentage should return to 100%. IF THAT DIDN'T WORK Ensure the filter is the correct model (it must be a genuine Dyson HEPA/Carbon Combi Filter for the BP04). Check that the filter is fully and correctly seated by removing and reinstalling it, aligning the arrows on the filter with the unit. HEADS UP The machine will not automatically detect a new filter. You must perform reset in the app every time. Failure to reset it will cause the machine to incorrectly indicate 0% and may affect performance logic.

Dyson Purifier Big Quiet BP04 Formaldehyde

Other Portable AC & Fans