diff --git a/fhem/FHEM/14_CUL_TX.pm b/fhem/FHEM/14_CUL_TX.pm
index 9343d9e47..4b12f1b19 100644
--- a/fhem/FHEM/14_CUL_TX.pm
+++ b/fhem/FHEM/14_CUL_TX.pm
@@ -20,7 +20,9 @@ CUL_TX_Initialize($)
   $hash->{AttrList}  = "IODev do_not_notify:1,0 ignore:0,1 showtime:1,0 " .
                         $readingFnAttributes;
   $hash->{AutoCreate}=
-        { "CUL_TX.*" => { GPLOT => "temp4hum4:Temp/Hum,", FILTER => "%NAME" } };
+        { "CUL_TX.*" => { GPLOT => "temp4hum4:Temp/Hum,",
+                          FILTER => "%NAME",
+                          autocreateThreshold => "2:180" } };
 }
 
 #############################
@@ -33,6 +35,12 @@ CUL_TX_Define($$)
   return "wrong syntax: define <name> CUL_TX <code> [corr] [minsecs]"
         if(int(@a) < 3 || int(@a) > 5);
 
+  my $dp = $modules{CUL_TX}{defptr};
+  my $old = ($dp && $dp->{$a[2]} ? $dp->{$a[2]}{NAME} : "");
+  my $op = ($hash->{OLDDEF} ? "modify":"define");
+  return "Cannot $op $hash->{NAME} as the code $a[2] is already used by $old"
+        if($old);
+
   $hash->{CODE} = $a[2];
   $hash->{corr} = ((int(@a) > 3) ? $a[3] : 0);
   $hash->{minsecs} = ((int(@a) > 4) ? $a[4] : 0);
@@ -75,7 +83,7 @@ CUL_TX_Parse($$)
   my $def = $modules{CUL_TX}{defptr}{$id3};
   if(!$def) {
     Log3 $hash, 2, "CUL_TX Unknown device $id3, please define it";
-    return "UNDEFINED CUL_TX_$id3 CUL_TX $id3" if(!$def);
+    return "UNDEFINED CUL_TX_$id3 CUL_TX $id3";
   }
   my $now = time();