diff --git a/control/example/events.yaml b/control/example/events.yaml
index ed62ce6..b2c22cf 100644
--- a/control/example/events.yaml
+++ b/control/example/events.yaml
@@ -32,7 +32,7 @@
 #groups:
 #    - name: zone0_fans
 #      description: Group of fan inventory objects for zone 0
-#      type: inventory
+#      type: /xyz/openbmc_project/inventory
 #      members:
 #          - /system/chassis/motherboard/fan0
 #          - /system/chassis/motherboard/fan1
@@ -40,9 +40,22 @@
 #          - /system/chassis/motherboard/fan3
 #    - name: zone0_ambient
 #      description: Group of ambient temperature sensors for zone 0
-#      type: sensors
+#      type: /xyz/openbmc_project/sensors
 #      members:
 #          - /temperature/ambient
+#    - name: occ0_object
+#      description: Dbus object containing OCC0 properties
+#      type: /org/open_power/control
+#      members:
+#          - /occ0
+#
+#preconditions:
+#    - name: property_states_match
+#      description: >
+#          All defined properties must match the values given to
+#          enable a set speed event otherwise fan speeds are set to full
+#      parameters:
+#          - groups
 #
 #actions:
 #    - name: count_state_before_speed
@@ -88,10 +101,10 @@
 #          name: set_floor_from_average_sensor_value
 #          map:
 #              value:
-#                  - 25: 3500
-#                  - 30: 4600
-#                  - 35: 5200
-#                  - 40: 5800
+#                  - 25000: 3500
+#                  - 30000: 4600
+#                  - 35000: 5200
+#                  - 40000: 5800
 #              type: std::map<int64_t, uint64_t>
 #    - name: update_water_cooled_floor_speed_based_on_ambient
 #      zone_conditions:
@@ -107,8 +120,37 @@
 #          name: set_floor_from_average_sensor_value
 #          map:
 #              value:
-#                  - 25: 2500
-#                  - 30: 3600
-#                  - 35: 4200
-#                  - 40: 4800
+#                  - 25000: 2500
+#                  - 30000: 3600
+#                  - 35000: 4200
+#                  - 40000: 4800
+#              type: std::map<int64_t, uint64_t>
+#    - name: update_ceiling_speed_based_on_ambient
+#      zone_conditions:
+#          - name: air_cooled_chassis
+#            zones:
+#                - 0
+#          - name: water_and_air_cooled_chassis
+#            zones:
+#                - 0
+#      precondition:
+#          name: property_states_match
+#          groups:
+#              - name: occ0_object
+#                interface: org.open_power.OCC.Status
+#                property:
+#                    name: OccActive
+#                    type: bool
+#                    value: true
+#      group: zone0_ambient
+#      interface: xyz.openbmc_project.Sensor.Value
+#      property:
+#          name: Value
+#          type: int64_t
+#      action:
+#          name: set_ceiling_from_average_sensor_value
+#          map:
+#              value:
+#                  - 25000: 7200
+#                  - 27000: 10500
 #              type: std::map<int64_t, uint64_t>
diff --git a/control/gen-fan-zone-defs.py b/control/gen-fan-zone-defs.py
index 177bfe0..ea05a0f 100755
--- a/control/gen-fan-zone-defs.py
+++ b/control/gen-fan-zone-defs.py
@@ -17,6 +17,7 @@
 #include "functor.hpp"
 #include "actions.hpp"
 #include "handlers.hpp"
+#include "preconditions.hpp"
 
 using namespace phosphor::fan::control;
 using namespace sdbusplus::bus::match::rules;
@@ -66,6 +67,32 @@
                 },
                 std::vector<SetSpeedEvent>{
                 %for event in zone['events']:
+                    %if ('pc' in event) and \
+                        (event['pc'] is not None):
+                    SetSpeedEvent{
+                        Group{
+                        %for member in event['pc']['pcgrp']:
+                        {
+                            "${member['name']}",
+                            {"${member['interface']}",
+                             "${member['property']}"}
+                        },
+                        %endfor
+                        },
+                        make_action(
+                            precondition::${event['pc']['pcact']['name']}(
+                        %for i, p in enumerate(event['pc']['pcact']['params']):
+                        ${p['type']}${p['open']}
+                        %for j, v in enumerate(p['values']):
+                        %if (j+1) != len(p['values']):
+                            ${v['value']},
+                        %else:
+                            ${v['value']}
+                        %endif
+                        %endfor
+                        ${p['close']},
+                        %endfor
+                    %endif
                     SetSpeedEvent{
                         Group{
                         %for member in event['group']:
@@ -105,6 +132,43 @@
                             },
                         %endfor
                         }
+                    %if ('pc' in event) and (event['pc'] is not None):
+                    }
+                        )),
+                        std::vector<PropertyChange>{
+                        %for s in event['pc']['pcsig']:
+                            PropertyChange{
+                                interfacesAdded("${s['obj_path']}"),
+                                make_handler(objectSignal<${s['type']}>(
+                                    "${s['path']}",
+                                    "${s['interface']}",
+                                    "${s['property']}",
+                                    handler::setProperty<${s['type']}>(
+                                        "${s['path']}",
+                                        "${s['interface']}",
+                                        "${s['property']}"
+                                    )
+                                ))
+                            },
+                            PropertyChange{
+                                interface("org.freedesktop.DBus.Properties") +
+                                member("PropertiesChanged") +
+                                type::signal() +
+                                path("${s['path']}") +
+                                arg0namespace("${s['interface']}"),
+                                make_handler(propertySignal<${s['type']}>(
+                                    "${s['interface']}",
+                                    "${s['property']}",
+                                    handler::setProperty<${s['type']}>(
+                                        "${s['path']}",
+                                        "${s['interface']}",
+                                        "${s['property']}"
+                                    )
+                                ))
+                            },
+                        %endfor
+                        }
+                    %endif
                     },
                 %endfor
                 }
@@ -127,6 +191,73 @@
     return listOfDict
 
 
+def addPrecondition(event, events_data):
+    """
+    Parses the precondition section of an event and populates the necessary
+    structures to generate a precondition for a set speed event.
+    """
+    precond = {}
+    # Add set speed event precondition group
+    group = []
+    for grp in event['precondition']['groups']:
+        groups = next(g for g in events_data['groups']
+                      if g['name'] == grp['name'])
+        for member in groups['members']:
+            members = {}
+            members['obj_path'] = groups['type']
+            members['name'] = (groups['type'] +
+                               member)
+            members['interface'] = grp['interface']
+            members['property'] = grp['property']['name']
+            members['type'] = grp['property']['type']
+            members['value'] = grp['property']['value']
+            group.append(members)
+    precond['pcgrp'] = group
+
+    # Add set speed event precondition action
+    pc = {}
+    pc['name'] = event['precondition']['name']
+    pcs = next(p for p in events_data['preconditions']
+               if p['name'] == event['precondition']['name'])
+    params = []
+    for p in pcs['parameters']:
+        param = {}
+        if p == 'groups':
+            param['type'] = "std::vector<PrecondGroup>"
+            param['open'] = "{"
+            param['close'] = "}"
+            values = []
+            for pcgrp in group:
+                value = {}
+                value['value'] = (
+                    "PrecondGroup{\"" +
+                    str(pcgrp['name']) + "\",\"" +
+                    str(pcgrp['interface']) + "\",\"" +
+                    str(pcgrp['property']) + "\"," +
+                    "static_cast<" +
+                    str(pcgrp['type']).lower() + ">" +
+                    "(" + str(pcgrp['value']).lower() + ")}")
+                values.append(value)
+            param['values'] = values
+        params.append(param)
+    pc['params'] = params
+    precond['pcact'] = pc
+
+    # Add precondition property change signal handler
+    signal = []
+    for member in group:
+        signals = {}
+        signals['obj_path'] = member['obj_path']
+        signals['path'] = member['name']
+        signals['interface'] = member['interface']
+        signals['property'] = member['property']
+        signals['type'] = member['type']
+        signal.append(signals)
+    precond['pcsig'] = signal
+
+    return precond
+
+
 def getEventsInZone(zone_num, zone_conditions, events_data):
     """
     Constructs the event entries defined for each zone using the events yaml
@@ -151,6 +282,11 @@
                 continue
 
             event = {}
+            # Add precondition if given
+            if ('precondition' in e) and \
+               (e['precondition'] is not None):
+                event['pc'] = addPrecondition(e, events_data)
+
             # Add set speed event group
             group = []
             groups = next(g for g in events_data['groups']
@@ -158,8 +294,7 @@
             for member in groups['members']:
                 members = {}
                 members['type'] = groups['type']
-                members['name'] = ("/xyz/openbmc_project/" +
-                                   groups['type'] +
+                members['name'] = (groups['type'] +
                                    member)
                 members['interface'] = e['interface']
                 members['property'] = e['property']['name']