diff --git a/monitor/fan.cpp b/monitor/fan.cpp
new file mode 100644
index 0000000..b29eaab
--- /dev/null
+++ b/monitor/fan.cpp
@@ -0,0 +1,113 @@
+/**
+ * Copyright © 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <algorithm>
+#include <phosphor-logging/log.hpp>
+#include "fan.hpp"
+#include "types.hpp"
+
+namespace phosphor
+{
+namespace fan
+{
+namespace monitor
+{
+
+using namespace phosphor::logging;
+
+Fan::Fan(sdbusplus::bus::bus& bus,
+         std::shared_ptr<sd_event>&  events,
+         const FanDefinition& def) :
+    _bus(bus),
+    _name(std::get<fanNameField>(def)),
+    _deviation(std::get<fanDeviationField>(def)),
+    _numSensorFailsForNonFunc(std::get<numSensorFailsForNonfuncField>(def))
+{
+    auto& sensors = std::get<sensorListField>(def);
+
+    for (auto& s : sensors)
+    {
+        _sensors.emplace_back(
+            std::make_unique<TachSensor>(bus,
+                                         *this,
+                                         std::get<sensorNameField>(s),
+                                         std::get<hasTargetField>(s),
+                                         std::get<timeoutField>(def)));
+
+    }
+
+}
+
+
+uint64_t Fan::getTargetSpeed(const TachSensor& sensor)
+{
+    uint64_t target = 0;
+
+    if (sensor.hasTarget())
+    {
+        target = sensor.getTarget();
+    }
+    else
+    {
+        //The sensor doesn't support a target,
+        //so get it from another sensor.
+        auto s = std::find_if(_sensors.begin(), _sensors.end(),
+                              [](const auto& s)
+                              {
+                                  return s->hasTarget();
+                              });
+
+        if (s != _sensors.end())
+        {
+            target = (*s)->getTarget();
+        }
+    }
+
+    return target;
+}
+
+
+bool Fan::tooManySensorsNonfunctional()
+{
+    size_t numFailed =  std::count_if(_sensors.begin(), _sensors.end(),
+                                      [](const auto& s)
+                                      {
+                                          return !s->functional();
+                                      });
+
+    return (numFailed >= _numSensorFailsForNonFunc);
+}
+
+
+bool Fan::outOfRange(const TachSensor& sensor)
+{
+    auto actual = static_cast<uint64_t>(sensor.getInput());
+    auto target = getTargetSpeed(sensor);
+
+    uint64_t min = target * (100 - _deviation) / 100;
+    uint64_t max = target * (100 + _deviation) / 100;
+
+    if ((actual < min) || (actual > max))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+
+}
+}
+}