diff --git a/incomfortclient/__init__.py b/incomfortclient/__init__.py
index 0a451d3..b8f04e5 100644
--- a/incomfortclient/__init__.py
+++ b/incomfortclient/__init__.py
@@ -10,6 +10,8 @@
 from __future__ import annotations
 
 import logging
+from enum import IntEnum
+from typing import Any
 
 import aiohttp
 
@@ -29,45 +31,54 @@
 BITMASK_PUMP = 0x02  # pump state: on / off
 BITMASK_TAP = 0x04  # tap (DHW) state: function on / off
 
-# key label: displ_code
-DISPLAY_CODES: dict[int, str] = {
-    0: "opentherm",
-    15: "boiler ext.",
-    24: "frost",
-    37: "central heating rf",
-    51: "tapwater int.",
-    85: "sensortest",
-    102: "central heating",
-    126: "standby",
-    153: "postrun boiler",
-    170: "service",
-    204: "tapwater",
-    231: "postrun ch",
-    240: "boiler int.",
-    255: "buffer",
-}
-FAULT_CODES: dict[int, str] = {
-    0: "Sensor fault after self check",
-    1: "Temperature too high",
-    2: "S1 and S2 interchanged",
-    4: "No flame signal",
-    5: "Poor flame signal",
-    6: "Flame detection fault",
-    8: "Incorrect fan speed",
-    10: "Sensor fault S1",
-    11: "Sensor fault S1",
-    12: "Sensor fault S1",
-    13: "Sensor fault S1",
-    14: "Sensor fault S1",
-    20: "Sensor fault S2",
-    21: "Sensor fault S2",
-    22: "Sensor fault S2",
-    23: "Sensor fault S2",
-    24: "Sensor fault S2",
-    27: "Shortcut outside sensor temperature",
-    29: "Gas valve relay faulty",
-    30: "Gas valve relay faulty",
-}  # "0.0": "Low system pressure"
+ISSUE_URL = "https://github.com/jbouwh/incomfort-client/issues"
+
+
+class DiplayCode(IntEnum):
+    """Label to display code."""
+
+    UNKNOWN = -1
+    OPENTHERM = 0
+    BOILET_EXT = 15
+    FROST = 24
+    CENNTRAL_HEATING_RF = 37
+    TAPWATER_INT = 51
+    SENSOR_TEST = 85
+    CENNTRAL_HEATING = 102
+    STANDBY = 126
+    POSTRUN_BOYLER = 153
+    SERVICE = 170
+    TAPWATER = 204
+    POSTRUN_CH = 231
+    BOILER_INT = 240
+    BUFFER = 255
+
+
+class FaultCode(IntEnum):
+    """Label to fault code."""
+
+    UNKNOWN = -1
+    SENSOR_FAULT_AFTER_SELF_CHECK_E0: 0
+    CV_TEMPERATURE_TOO_HIGH_E1: 1
+    S1_AND_S2_INTERCHANGED_E2: 2
+    NO_FLAME_SIGNAL_E4: 4
+    POOR_FLAME_SIGNAL_E5: 5
+    FLAME_DETECTION_FAULT_E6: 6
+    INCORRECT_FAN_SPEED_E8: 8
+    SENSOR_FAULT_S1_E10: 10
+    SENSOR_FAULT_S1_E11: 11
+    SENSOR_FAULT_S1_E12: 12
+    SENSOR_FAULT_S1_E13: 13
+    SENSOR_FAULT_S1_E14: 14
+    SENSOR_FAULT_S2_E20: 20
+    SENSOR_FAULT_S2_E21: 21
+    SENSOR_FAULT_S2_E22: 22
+    SENSOR_FAULT_S2_E23: 23
+    SENSOR_FAULT_S2_E24: 24
+    SHORTCUT_OUTSIDE_SENSOR_TEMPERATURE_E27: 27
+    GAS_VALVE_RELAY_FAULTY_E29: 29
+    GAS_VALVE_RELAY_FAULTY_E30: 30
+
 
 HEATER_ATTRS: tuple[str, ...] = (
     "display_code",
@@ -221,11 +232,45 @@ def __init__(self, serial_no: str, idx: int, gateway: Gateway) -> None:
         self._data: dict = {}
         self._status: dict = {}
         self._rooms: list[Room] = None
+        self.display_code: DiplayCode | None = None
+        self.fault_code: FaultCode | None = None
+        self._last_display_code: int | None = None
 
     async def update(self) -> None:
         """Retrieve the Heater's latest status from the Gateway."""
         self._data = await self._get(f"data.json?heater={self._heater_idx}")
 
+        code: int = self._data["displ_code"]
+        if self.is_failed:
+            self.display_code = None
+            try:
+                self.fault_code = FaultCode(code)
+            except ValueError:
+                self.fault_code = FaultCode.UNKNOWN
+                if self._last_display_code != code:
+                    _LOGGER.warning(
+                        "Unknown fault code %s reported by heater %s. "
+                        "Log an issue at %s to report the unknown fault code",
+                        code,
+                        self._serial_no,
+                        ISSUE_URL,
+                    )
+        else:
+            self.fault_code = None
+            try:
+                self.display_code = DiplayCode(code)
+            except ValueError:
+                self.display_code = DiplayCode.UNKNOWN
+                if self._last_display_code != code:
+                    _LOGGER.warning(
+                        "Unknown operation code %s reported by heater %s"
+                        "Log an issue at %s to report the unknown display code",
+                        code,
+                        self._serial_no,
+                        ISSUE_URL,
+                    )
+        self._last_display_code = code
+
         self._status = {}
 
         for attr in HEATER_ATTRS:
@@ -237,26 +282,16 @@ async def update(self) -> None:
         _LOGGER.debug("Heater(%s).status() = %s", self._serial_no, self._status)
 
     @property
-    def status(self) -> dict:
+    def status(self) -> dict[str, Any]:
         """Return the current state of the heater."""
         return self._status
 
     @property
-    def display_code(self) -> int:
-        """Return the display code, 'displ_code'."""
-        return self._data["displ_code"]
-
-    @property
-    def display_text(self) -> None | str:
-        """Return the display code as text rather than a code."""
-        code = self.display_code
-        code_map = FAULT_CODES if self.is_failed else DISPLAY_CODES
-        return code_map.get(code, f"unknown/other, code = '{code}'")
-
-    @property
-    def fault_code(self) -> None | int:
-        """Return the fault code when the heater is in a failed state."""
-        return self._data["displ_code"] if self.is_failed else None
+    def display_text(self) -> str | None:
+        """Return the display or fault code as text label rather than a code."""
+        if self.is_failed:
+            return self.fault_code.name.lower() if self.fault_code else None
+        return self.display_code.name.lower() if self.display_code else None
 
     @property
     def is_burning(self) -> bool: