diff --git a/homeassistant/components/landisgyr_heat_meter/const.py b/homeassistant/components/landisgyr_heat_meter/const.py
index 55a6c65892c..57a8f9d9be4 100644
--- a/homeassistant/components/landisgyr_heat_meter/const.py
+++ b/homeassistant/components/landisgyr_heat_meter/const.py
@@ -44,6 +44,14 @@ HEAT_METER_SENSOR_TYPES = (
         native_unit_of_measurement=ENERGY_MEGA_WATT_HOUR,
         entity_category=EntityCategory.DIAGNOSTIC,
     ),
+    # Diagnostic entity for debugging, this will match the value in GJ of previous year indicated on the meter's display
+    SensorEntityDescription(
+        key="heat_previous_year_gj",
+        icon="mdi:fire",
+        name="Heat previous year GJ",
+        native_unit_of_measurement="GJ",
+        entity_category=EntityCategory.DIAGNOSTIC,
+    ),
     SensorEntityDescription(
         key="volume_previous_year_m3",
         icon="mdi:fire",
diff --git a/tests/components/landisgyr_heat_meter/test_sensor.py b/tests/components/landisgyr_heat_meter/test_sensor.py
index 505efb446b8..1a068093d0e 100644
--- a/tests/components/landisgyr_heat_meter/test_sensor.py
+++ b/tests/components/landisgyr_heat_meter/test_sensor.py
@@ -76,7 +76,7 @@ async def test_create_sensors(mock_heat_meter, hass):
     await hass.async_block_till_done()
 
     # check if 26 attributes have been created
-    assert len(hass.states.async_all()) == 26
+    assert len(hass.states.async_all()) == 27
     entity_reg = entity_registry.async_get(hass)
 
     state = hass.states.get("sensor.heat_meter_heat_usage")