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🔁 MQTT Retain (optional)

To ensure Home Assistant and other clients immediately see the last known state after a restart, the bridge can publish its republished MQTT messages with the Retain flag.

Default: off (MQTT_RETAIN=0)
When enabled: Retain applies to: - bmw/raw/<VIN>/<eventName> - bmw/<VIN>/<eventName> (Legacy) - bmw/vehicles/<VIN>/<propertyName> (when SPLIT_TOPICS=1)

The status topic bmw/status is always retained (LWT), regardless of this setting, to keep availability tracking consistent.

Enable

edit the file: .env 

MQTT_RETAIN=1

Clean up (remove retained messages)

If you want to clear a topic:

# remove retained message (send empty retained message)
mosquitto_pub -t 'bmw/vehicles/<VIN>/range_km' -r -n

or, alternatively, use MQTT Explorer

Notes

  • For stateful topics (e.g. door lock, availability, battery values) retain is very useful.
  • For high-frequency or transient topics, retain may be undesirable (it shows an outdated snapshot).
  • If you later change your LOCAL_PREFIX, old retained messages under the previous prefix will remain in your broker until you remove them manually (see above).