diff --git a/src/aiovantage/command_client/commands.py b/src/aiovantage/command_client/commands.py
index 1cfa126..21ab8c5 100644
--- a/src/aiovantage/command_client/commands.py
+++ b/src/aiovantage/command_client/commands.py
@@ -15,6 +15,7 @@
     InvalidObjectError,
     LoginFailedError,
     LoginRequiredError,
+    ObjectOfflineError,
 )
 
 from .utils import encode_params, tokenize_response
@@ -187,6 +188,8 @@ def _parse_command_error(self, message: str) -> CommandError:
         exc: CommandError
         if error_code == 7:
             exc = InvalidObjectError(error_message)
+        elif error_code == 20:
+            exc = ObjectOfflineError(error_message)
         elif error_code == 21:
             exc = LoginRequiredError(error_message)
         elif error_code == 23:
diff --git a/src/aiovantage/errors.py b/src/aiovantage/errors.py
index cd8a9dd..2135893 100644
--- a/src/aiovantage/errors.py
+++ b/src/aiovantage/errors.py
@@ -33,3 +33,7 @@ class LoginRequiredError(CommandError):
 
 class InvalidObjectError(CommandError):
     """The requested object ID is invalid."""
+
+
+class ObjectOfflineError(CommandError):
+    """The requested object is offline."""