diff --git a/datatypes/epc/domain/mapper.py b/datatypes/epc/domain/mapper.py
index e9e72ab6c..a9f9e5cae 100644
--- a/datatypes/epc/domain/mapper.py
+++ b/datatypes/epc/domain/mapper.py
@@ -7030,6 +7030,30 @@ def _elmhurst_main_fuel_int(fuel_type: str) -> Optional[int]:
     return _ELMHURST_MAIN_FUEL_TO_SAP10.get(fuel_type)
 
 
+class UnmappedPasHubLabel(ValueError):
+    """A PasHub Site-Notes survey lodged a finite-enum label that the mapper
+    does not yet know how to translate to the SAP10 cascade enum.
+
+    Raised by the strict PasHub label-to-code helpers to surface mapper-
+    coverage gaps at the `from_site_notes` boundary (ADR-0015) instead of
+    passing the raw string downstream, where it resurfaces as the
+    calculator's deep `MissingMainFuelType` raise — or worse, is silently
+    mis-billed. Mirrors `UnmappedApiCode` / `UnmappedElmhurstLabel`.
+
+    Distinguish "lodging absent" (a genuinely blank cell — the helper returns
+    it unchanged, correct) from "lodging present but unrecognised" (raise —
+    a Fuel label the lookup doesn't yet cover, needs a dict entry added).
+    """
+
+    def __init__(self, field: str, value: str) -> None:
+        super().__init__(
+            f"unmapped PasHub {field} label: {value!r}; "
+            f"add an entry to the corresponding mapper lookup dict"
+        )
+        self.field = field
+        self.value = value
+
+
 # PasHub Site-Notes surveyed main-heating "Fuel" labels mapped to SAP10 fuel
 # codes (the epc-codes `main_fuel` enum the calculator's resolver routes via
 # its API→Table-12/32 translation). Seeded only with labels confirmed from
diff --git a/datatypes/epc/domain/tests/test_from_site_notes.py b/datatypes/epc/domain/tests/test_from_site_notes.py
index 81670e239..52598b720 100644
--- a/datatypes/epc/domain/tests/test_from_site_notes.py
+++ b/datatypes/epc/domain/tests/test_from_site_notes.py
@@ -820,3 +820,25 @@ class TestElmhurstSecondaryFuelFromSapCode:
         # Act / Assert
         with pytest.raises(UnmappedElmhurstLabel):
             _elmhurst_secondary_fuel_from_sap_code(620)
+
+
+class TestPasHubUnmappedMainFuel:
+    """A PasHub survey whose surveyed main-heating Fuel label the mapper does
+    not yet cover must strict-raise `UnmappedPasHubLabel` at the boundary,
+    naming the label — so a coverage gap is fixed here (a one-line lookup
+    addition) rather than passed downstream as a raw string to resurface as
+    the calculator's `MissingMainFuelType`, or silently mis-billed.
+    """
+
+    def test_unrecognised_fuel_label_raises_naming_the_label(self) -> None:
+        # Arrange — an example fixture whose Fuel cell carries a label the
+        # PasHub lookup does not yet know.
+        from datatypes.epc.domain.mapper import UnmappedPasHubLabel
+
+        raw = load("pashub_rdsap_site_notes_example1.json")
+        raw["heating_and_hot_water"]["main_heating"]["fuel"] = "Anthracite"
+        survey = from_dict(PasHubRdSapSiteNotes, raw)
+
+        # Act / Assert
+        with pytest.raises(UnmappedPasHubLabel, match="Anthracite"):
+            EpcPropertyDataMapper.from_site_notes(survey)