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Troubleshooting

Rapidly flashing red status LED on a VLAN without internet

If your UltimateSensor v2 continues to report measurements but its red status LED flashes rapidly after startup, the firmware update check may be blocked by your firewall or IoT VLAN.

The local UltimateSensor v2 firmware reads a small version manifest from SmartHomeShop GitHub Pages. This check only determines whether new firmware is available. It does not send sensor readings, Home Assistant data, Wi-Fi passwords or API keys to GitHub.

ESPHome's standard status LED reports errors from every firmware component. A blocked update check can therefore look like a device startup error even while UltimateSensor v2 itself is working normally.

Confirm the cause

Open the UltimateSensor v2 logs in ESPHome and look for http_request.update or Failed to fetch manifest. If these messages are not present, investigate power, network and sensor initialization before changing the update settings.

Disable scheduled firmware checks

  1. Open the ESPHome Device Builder app/add-on in Home Assistant. This is different from the ESPHome integration under Settings > Devices & services.
  2. Find UltimateSensor v2 and select Take control or Adopt.
  3. Save a copy of the generated YAML, including its API encryption key.
  4. Select Edit and add this block at the bottom of the YAML, without extra indentation:
update:
  - id: !extend firmware_update
    update_interval: never
  1. Save the file, select Validate, and then select Install > Wirelessly.

After installation, UltimateSensor v2 keeps measuring and communicating locally with Home Assistant, but it no longer performs scheduled firmware checks. You can still update it later through ESPHome or the SmartHomeShop web flasher.

ESPHome still downloads the UltimateSensor v2 packages: configuration from GitHub while compiling. That request is made by the Home Assistant/ESPHome host, not by UltimateSensor v2 itself.

If validation says that firmware_update does not exist, remove the block again and install a current UltimateSensor v2 firmware version first. A rapidly flashing LED that remains after this change can indicate another real firmware or hardware error.

This guide covers common UltimateSensor v2 issues.

mmWave Radar Issues

Standard firmware uses LD2450 for zones and target tracking. If LD2460 upgrade firmware is installed, LD2460 physically replaces LD2450. Use its target 1-5 X/Y/Distance/Angle entities with the shared Room Designer polygon and exclusion zones.

Presence Always On

Fix

  1. Empty the room completely.
  2. Stop fans, moving curtains and other moving objects.
  3. Run the LD2412 background calibration. The LD2412 Dynamic Background Correction button is disabled by default, so enable it first.
  4. Lower LD2412 Maximum Distance Gate if the room is smaller than the configured range.
  5. Tighten LD2450 Zone boundaries, or adjust LD2460 placement/filtering if the upgrade firmware is installed.

Detecting Through Walls

mmWave radar can detect through thin drywall, wood and some furniture.

Fix

  • Lower LD2412 maximum distance gate.
  • Tighten LD2450 Zone 1 X1/Y1/X2/Y2 boundaries.
  • Move LD2450 zone boundaries away from walls.
  • On LD2460 firmware, verify mounting height and angle, reduce the hardware detection sector and tighten Room Designer zones.

No Detection

Fix

  • Increase LD2412 Maximum Distance Gate if the range is too short.
  • Check the sensor is aimed at the monitored area.
  • Check that zones are not too small.
  • Factory reset radar settings and recalibrate if needed.

Zone Occupancy Is Wrong

Fix

  • Confirm LD2450 X/Y coordinates while walking around the room.
  • If LD2460 firmware is installed, confirm target 1-5 X/Y/Distance/Angle values and the shared Room Designer zones.
  • Set zone X boundaries left/right of the target area.
  • Set Y boundaries from near to far distance.
  • Increase occupancy off delay if the zone flickers.

PIR Issues

PIR Does Not Trigger

  • PIR requires line of sight.
  • Make sure the front of the sensor faces the movement area.
  • PIR detects heat movement; mmWave is more reliable for still presence.

PIR Triggers but Presence Turns Off Too Soon

Use PIR only as the quick trigger. Keep lights or automations active based on LD2412/LD2450 presence, or LD2412/LD2460 presence if the optional LD2460 upgrade is installed.

Voice Assistant Issues

Wake Word Not Responding

  • Confirm Use Wake Word is enabled. On cloud firmware this switch is called Cloud Voice.
  • Check the Assist pipeline configuration in Home Assistant.
  • Test the media player with a short TTS message.
  • Avoid placing the device near TVs, speakers, fans or other constant noise sources.
  • See Voice Assistant Guide.

No Audio Output

  • Check the media player entity is available.
  • Try a simple TTS test.
  • Check volume and pipeline settings in Home Assistant.

CO2 and Climate Issues

CO2 Looks Wrong

  1. Ventilate the room with fresh air.
  2. Wait until readings stabilize.
  3. Press CO2 Manual Calibration. This button is disabled by default, so enable it first.
  4. Do not calibrate with people in the room.

Temperature Too High

  • Avoid direct sunlight and heat sources.
  • Compare with a reliable thermometer after 20-30 minutes.
  • For a small correction, use the Temperature Offset entity. For a permanent correction, raise the scd41_temperature_offset substitution in ESPHome and reflash: a higher value lowers the reading.

VOC or NOx Seems Unstable

SGP41 values are relative indexes and need runtime to stabilize after flashing, moving or long power-off periods.

SPS30 Issues

No PM Values

  • Confirm SPS30 is installed.
  • Confirm Complete firmware is installed.
  • Wait for initialization.
  • Check hidden entities in Home Assistant.

Network Issues

Hotspot Not Visible

  • The fallback SSID is ultimatesensor (older firmware: ultimatesensor-v2).
  • The fallback password is the same as the SSID.
  • The hotspot only appears if WiFi is not configured or connection fails.
  • Power cycle and wait 1-2 minutes.
  • Open http://192.168.4.1/ manually if captive portal does not open.

Ethernet or PoE Not Working

  • Ethernet requires Ethernet firmware.
  • Connect Ethernet before switching to Ethernet firmware.
  • Check PoE switch/injector compatibility.
  • Check your router DHCP list for the new IP address.

Entities Missing in Home Assistant

  • Some entities are disabled by default, such as CO2 Manual Calibration, LD2412 Dynamic Background Correction, Factory Reset and the firmware update entity.
  • Open the device in Home Assistant and enable hidden entities.
  • LD2460 entities only appear when the matching *-ld2460.yaml firmware is flashed on hardware where LD2460 replaces LD2450.

Feature Confusion

UltimateSensor v2 does not have:

  • Barometric pressure
  • ESP32-C6 hardware platform

Mini v2 does have ESP32-C6, but does not have voice assistant, speaker, microphone or PIR.

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