diff --git a/src/lang/english.txt b/src/lang/english.txt
index 059c791..f65350e 100644
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -4448,6 +4448,10 @@ STR_ERROR_CAN_T_STOP_SHARING_ORDER_LIST                         :{WHITE}Can't st
 STR_ERROR_CAN_T_COPY_ORDER_LIST                                 :{WHITE}Can't copy order list...
 STR_ERROR_TOO_FAR_FROM_PREVIOUS_DESTINATION                     :{WHITE}... too far from previous destination
 STR_ERROR_AIRCRAFT_NOT_ENOUGH_RANGE                             :{WHITE}... aircraft has not enough range
+#related to conditional Orders
+STR_ERROR_COND_ORDER_ALWAYS_TRUE                                :{WHITE}Condition of conditional order is always true
+STR_ERROR_COND_ORDER_ALWAYS_FALSE                               :{WHITE}Condition of conditional order is always false
+STR_ERROR_COND_ORDER_NO_SERVICING                               :{WHITE}Servicing was disabled in settings.
 
 # Timetable related errors
 STR_ERROR_CAN_T_TIMETABLE_VEHICLE                               :{WHITE}Can't timetable vehicle...
diff --git a/src/order_cmd.cpp b/src/order_cmd.cpp
index 57b29f3..2a31900 100644
--- a/src/order_cmd.cpp
+++ b/src/order_cmd.cpp
@@ -28,6 +28,7 @@
 #include "company_base.h"
 #include "order_backup.h"
 #include "cheat_type.h"
+#include "error.h"
 
 #include "table/strings.h"
 
@@ -1292,6 +1293,7 @@ CommandCost CmdModifyOrder(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 	VehicleID veh          = GB(p1,  0, 20);
 	ModifyOrderFlags mof   = Extract<ModifyOrderFlags, 0, 4>(p2);
 	uint16 data            = GB(p2,  4, 11);
+	bool cond_order_needs_check = false; //Should get set to true, if a conditional order is modified
 
 	if (mof >= MOF_END) return CMD_ERROR;
 
@@ -1449,8 +1451,10 @@ CommandCost CmdModifyOrder(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 			}
 
 			case MOF_COND_VARIABLE: {
+				cond_order_needs_check = true;
 				order->SetConditionVariable((OrderConditionVariable)data);
 
+
 				OrderConditionComparator occ = order->GetConditionComparator();
 				switch (order->GetConditionVariable()) {
 					case OCV_UNCONDITIONALLY:
@@ -1475,20 +1479,87 @@ CommandCost CmdModifyOrder(TileIndex tile, DoCommandFlag flags, uint32 p1, uint3
 			}
 
 			case MOF_COND_COMPARATOR:
+				cond_order_needs_check = true;
 				order->SetConditionComparator((OrderConditionComparator)data);
 				break;
 
 			case MOF_COND_VALUE:
+				cond_order_needs_check = true;
 				order->SetConditionValue(data);
 				break;
 
 			case MOF_COND_DESTINATION:
+				cond_order_needs_check = true;
 				order->SetConditionSkipToOrder(data);
 				break;
 
 			default: NOT_REACHED();
 		}
 
+		/* Check if a Conditional order is always true or always false */
+		if (cond_order_needs_check) {
+			OrderConditionVariable ocvar = order->GetConditionVariable();
+
+			/* If servicing is disabled, you shouldn't check, if the vehicle needs servicing */
+			if (ocvar == OCV_REQUIRES_SERVICE && _settings_game.order.no_servicing_if_no_breakdowns == true && _settings_game.difficulty.vehicle_breakdowns == 0) {
+				ShowErrorMessage(STR_ERROR_COND_ORDER_NO_SERVICING, INVALID_STRING_ID, WL_WARNING);
+			}
+
+			/* No need to check an unconditional jump */
+			if (ocvar !=OCV_UNCONDITIONALLY) {
+				OrderConditionComparator occ = order->GetConditionComparator();
+				const uint16 ocval = order->GetConditionValue();
+
+				/* >= 0 is always true, since the value is unsigned
+				 * <0 is always false */
+				if (ocval == 0) {
+					switch (occ) {
+						case OCC_MORE_EQUALS:
+							ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_TRUE, INVALID_STRING_ID, WL_WARNING);
+							break;
+						case OCC_LESS_THAN:
+							ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_FALSE, INVALID_STRING_ID, WL_WARNING);
+							break;
+						default:
+							break;
+					}
+				}
+
+				/* for Percentages, <= 100 is always true
+				 * >100 is always false*/
+				if (ocval == 100) {
+					switch (ocvar) {
+						case OCV_LOAD_PERCENTAGE:
+						case OCV_RELIABILITY: //Deliberate Passthrough
+							if (occ == OCC_LESS_EQUALS) {
+								ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_TRUE, INVALID_STRING_ID, WL_WARNING);
+							}
+							if (occ == OCC_MORE_THAN) {
+								ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_FALSE, INVALID_STRING_ID, WL_WARNING);
+							}
+							break;
+						default:
+							break;
+					}
+				}
+
+				/* In general, the maximum is 2047, so <=2047 is always true,
+				 * >2047 is always false */
+				if (ocval == 2047) {
+					switch (occ) {
+						case OCC_LESS_EQUALS:
+							ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_TRUE, INVALID_STRING_ID, WL_WARNING);
+							break;
+						case OCC_MORE_THAN:
+							ShowErrorMessage(STR_ERROR_COND_ORDER_ALWAYS_FALSE, INVALID_STRING_ID, WL_WARNING);
+							break;
+						default:
+							break;
+					}
+				}
+			}
+		}
+
 		/* Update the windows and full load flags, also for vehicles that share the same order list */
 		Vehicle *u = v->FirstShared();
 		DeleteOrderWarnings(u);