diff --git a/phosphor-regulators/src/meson.build b/phosphor-regulators/src/meson.build
index 8238d93..7b852bb 100644
--- a/phosphor-regulators/src/meson.build
+++ b/phosphor-regulators/src/meson.build
@@ -15,6 +15,7 @@
     'id_map.cpp',
     'journal.cpp',
     'pmbus_utils.cpp',
+    'presence_detection.cpp',
     'presence_service.cpp',
     'rail.cpp',
     'sensor_monitoring.cpp',
diff --git a/phosphor-regulators/src/presence_detection.cpp b/phosphor-regulators/src/presence_detection.cpp
new file mode 100644
index 0000000..3ed5350
--- /dev/null
+++ b/phosphor-regulators/src/presence_detection.cpp
@@ -0,0 +1,64 @@
+/**
+ * Copyright © 2020 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 "presence_detection.hpp"
+
+#include "action_environment.hpp"
+#include "action_utils.hpp"
+#include "chassis.hpp"
+#include "device.hpp"
+#include "exception_utils.hpp"
+#include "system.hpp"
+
+#include <exception>
+
+namespace phosphor::power::regulators
+{
+
+bool PresenceDetection::execute(Services& services, System& system,
+                                Chassis& /*chassis*/, Device& device)
+{
+    // If no presence value is cached
+    if (!isPresent.has_value())
+    {
+        // Initially assume device is present
+        isPresent = true;
+
+        // Execute actions to find device presence
+        try
+        {
+            // Create ActionEnvironment
+            ActionEnvironment environment{system.getIDMap(), device.getID(),
+                                          services};
+
+            // Execute the actions and cache resulting value
+            isPresent = action_utils::execute(actions, environment);
+        }
+        catch (const std::exception& e)
+        {
+            // Log error messages in journal
+            services.getJournal().logError(exception_utils::getMessages(e));
+            services.getJournal().logError("Unable to determine presence of " +
+                                           device.getID());
+
+            // TODO: Create error log entry
+        }
+    }
+
+    return isPresent.value();
+}
+
+} // namespace phosphor::power::regulators
diff --git a/phosphor-regulators/src/presence_detection.hpp b/phosphor-regulators/src/presence_detection.hpp
index 23f416c..0574003 100644
--- a/phosphor-regulators/src/presence_detection.hpp
+++ b/phosphor-regulators/src/presence_detection.hpp
@@ -16,14 +16,21 @@
 #pragma once
 
 #include "action.hpp"
+#include "services.hpp"
 
 #include <memory>
+#include <optional>
 #include <utility>
 #include <vector>
 
 namespace phosphor::power::regulators
 {
 
+// Forward declarations to avoid circular dependencies
+class Chassis;
+class Device;
+class System;
+
 /**
  * @class PresenceDetection
  *
@@ -69,20 +76,30 @@
     }
 
     /**
+     * Clears the cached presence value.
+     */
+    void clearCache(void)
+    {
+        isPresent.reset();
+    }
+
+    /**
      * Executes the actions to detect whether the device is present.
      *
      * The return value of the last action indicates whether the device is
      * present.  A return value of true means the device is present; false means
      * the device is missing.
      *
+     * Caches the resulting presence value.  Subsequent calls to execute() will
+     * return the cached value rather than re-executing the actions.  This
+     * provides a performance improvement since the actions may be expensive to
+     * execute, such as I2C reads or D-Bus method calls.  The cached value can
+     * be cleared by calling clearCache().
+     *
      * @return true if device is present, false otherwise
      */
-    bool execute()
-    {
-        // TODO: Create ActionEnvironment, execute actions, catch and handle any
-        // exceptions
-        return true;
-    }
+    bool execute(Services& services, System& system, Chassis& chassis,
+                 Device& device);
 
     /**
      * Returns the actions that detect whether the device is present.
@@ -94,11 +111,26 @@
         return actions;
     }
 
+    /**
+     * Returns the cached presence value, if any.
+     *
+     * @return cached presence value
+     */
+    std::optional<bool> getCachedPresence() const
+    {
+        return isPresent;
+    }
+
   private:
     /**
      * Actions that detect whether the device is present.
      */
     std::vector<std::unique_ptr<Action>> actions{};
+
+    /**
+     * Cached presence value.  Initially has no value.
+     */
+    std::optional<bool> isPresent{};
 };
 
 } // namespace phosphor::power::regulators
diff --git a/phosphor-regulators/test/presence_detection_tests.cpp b/phosphor-regulators/test/presence_detection_tests.cpp
index 7f3c10f..f489b7f 100644
--- a/phosphor-regulators/test/presence_detection_tests.cpp
+++ b/phosphor-regulators/test/presence_detection_tests.cpp
@@ -14,29 +14,252 @@
  * limitations under the License.
  */
 #include "action.hpp"
+#include "chassis.hpp"
+#include "compare_presence_action.hpp"
+#include "device.hpp"
+#include "i2c_interface.hpp"
 #include "mock_action.hpp"
+#include "mock_journal.hpp"
+#include "mock_presence_service.hpp"
+#include "mock_services.hpp"
+#include "mocked_i2c_interface.hpp"
 #include "presence_detection.hpp"
+#include "rule.hpp"
+#include "system.hpp"
 
 #include <memory>
+#include <stdexcept>
+#include <string>
+#include <tuple>
 #include <utility>
 #include <vector>
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
 using namespace phosphor::power::regulators;
 
+using ::testing::Return;
+using ::testing::Throw;
+
+/**
+ * Creates the parent objects that normally contain a PresenceDetection object.
+ *
+ * A PresenceDetection object is normally contained within a hierarchy of
+ * System, Chassis, and Device objects.  These objects are required in order to
+ * call the execute() method.
+ *
+ * Creates the System, Chassis, and Device objects.  The PresenceDetection
+ * object is moved into the Device object.
+ *
+ * @param detection PresenceDetection object to move into object hierarchy
+ * @return Pointers to the System, Chassis, and Device objects.  The Chassis and
+ *         Device objects are contained within the System object and will be
+ *         automatically destructed.
+ */
+std::tuple<std::unique_ptr<System>, Chassis*, Device*>
+    createParentObjects(std::unique_ptr<PresenceDetection> detection)
+{
+    // Create mock I2CInterface
+    std::unique_ptr<i2c::MockedI2CInterface> i2cInterface =
+        std::make_unique<i2c::MockedI2CInterface>();
+
+    // Create Device that contains PresenceDetection
+    std::unique_ptr<Device> device = std::make_unique<Device>(
+        "vdd_reg", true,
+        "/xyz/openbmc_project/inventory/system/chassis/motherboard/reg2",
+        std::move(i2cInterface), std::move(detection));
+    Device* devicePtr = device.get();
+
+    // Create Chassis that contains Device
+    std::vector<std::unique_ptr<Device>> devices{};
+    devices.emplace_back(std::move(device));
+    std::unique_ptr<Chassis> chassis =
+        std::make_unique<Chassis>(1, std::move(devices));
+    Chassis* chassisPtr = chassis.get();
+
+    // Create System that contains Chassis
+    std::vector<std::unique_ptr<Rule>> rules{};
+    std::vector<std::unique_ptr<Chassis>> chassisVec{};
+    chassisVec.emplace_back(std::move(chassis));
+    std::unique_ptr<System> system =
+        std::make_unique<System>(std::move(rules), std::move(chassisVec));
+
+    return std::make_tuple(std::move(system), chassisPtr, devicePtr);
+}
+
 TEST(PresenceDetectionTests, Constructor)
 {
     std::vector<std::unique_ptr<Action>> actions{};
-    actions.push_back(std::make_unique<MockAction>());
+    actions.emplace_back(std::make_unique<MockAction>());
 
-    PresenceDetection presenceDetection(std::move(actions));
-    EXPECT_EQ(presenceDetection.getActions().size(), 1);
+    PresenceDetection detection{std::move(actions)};
+    EXPECT_EQ(detection.getActions().size(), 1);
+    EXPECT_FALSE(detection.getCachedPresence().has_value());
+}
+
+TEST(PresenceDetectionTests, ClearCache)
+{
+    // Create MockAction that will return true once
+    std::unique_ptr<MockAction> action = std::make_unique<MockAction>();
+    EXPECT_CALL(*action, execute).Times(1).WillOnce(Return(true));
+
+    // Create PresenceDetection
+    std::vector<std::unique_ptr<Action>> actions{};
+    actions.emplace_back(std::move(action));
+    PresenceDetection* detection = new PresenceDetection(std::move(actions));
+
+    // Create parent System, Chassis, and Device objects
+    auto [system, chassis, device] =
+        createParentObjects(std::unique_ptr<PresenceDetection>{detection});
+
+    // Verify that initially no presence value is cached
+    EXPECT_FALSE(detection->getCachedPresence().has_value());
+
+    // Call execute() which should obtain and cache presence value
+    MockServices services{};
+    EXPECT_TRUE(detection->execute(services, *system, *chassis, *device));
+
+    // Verify true presence value was cached
+    EXPECT_TRUE(detection->getCachedPresence().has_value());
+    EXPECT_TRUE(detection->getCachedPresence().value());
+
+    // Clear cached presence value
+    detection->clearCache();
+
+    // Verify that no presence value is cached
+    EXPECT_FALSE(detection->getCachedPresence().has_value());
 }
 
 TEST(PresenceDetectionTests, Execute)
 {
-    // TODO: Implement test when execute() function is done
+    // Create ComparePresenceAction
+    std::unique_ptr<ComparePresenceAction> action =
+        std::make_unique<ComparePresenceAction>(
+            "/xyz/openbmc_project/inventory/system/chassis/motherboard/cpu2",
+            true);
+
+    // Create PresenceDetection
+    std::vector<std::unique_ptr<Action>> actions{};
+    actions.emplace_back(std::move(action));
+    PresenceDetection* detection = new PresenceDetection(std::move(actions));
+
+    // Create parent System, Chassis, and Device objects
+    auto [system, chassis, device] =
+        createParentObjects(std::unique_ptr<PresenceDetection>{detection});
+
+    // Test where works: Present: Value is not cached
+    {
+        EXPECT_FALSE(detection->getCachedPresence().has_value());
+
+        // Create MockServices.  MockPresenceService::isPresent() should return
+        // true.
+        MockServices services{};
+        MockPresenceService& presenceService =
+            services.getMockPresenceService();
+        EXPECT_CALL(presenceService,
+                    isPresent("/xyz/openbmc_project/inventory/system/chassis/"
+                              "motherboard/cpu2"))
+            .Times(1)
+            .WillOnce(Return(true));
+
+        // Execute PresenceDetection
+        EXPECT_TRUE(detection->execute(services, *system, *chassis, *device));
+
+        EXPECT_TRUE(detection->getCachedPresence().has_value());
+        EXPECT_TRUE(detection->getCachedPresence().value());
+    }
+
+    // Test where works: Present: Value is cached
+    {
+        EXPECT_TRUE(detection->getCachedPresence().has_value());
+
+        // Create MockServices.  MockPresenceService::isPresent() should not be
+        // called.
+        MockServices services{};
+        MockPresenceService& presenceService =
+            services.getMockPresenceService();
+        EXPECT_CALL(presenceService, isPresent).Times(0);
+
+        // Execute PresenceDetection
+        EXPECT_TRUE(detection->execute(services, *system, *chassis, *device));
+    }
+
+    // Test where works: Not present: Value is not cached
+    {
+        // Clear cached presence value
+        detection->clearCache();
+        EXPECT_FALSE(detection->getCachedPresence().has_value());
+
+        // Create MockServices.  MockPresenceService::isPresent() should return
+        // false.
+        MockServices services{};
+        MockPresenceService& presenceService =
+            services.getMockPresenceService();
+        EXPECT_CALL(presenceService,
+                    isPresent("/xyz/openbmc_project/inventory/system/chassis/"
+                              "motherboard/cpu2"))
+            .Times(1)
+            .WillOnce(Return(false));
+
+        // Execute PresenceDetection
+        EXPECT_FALSE(detection->execute(services, *system, *chassis, *device));
+
+        EXPECT_TRUE(detection->getCachedPresence().has_value());
+        EXPECT_FALSE(detection->getCachedPresence().value());
+    }
+
+    // Test where works: Not present: Value is cached
+    {
+        EXPECT_TRUE(detection->getCachedPresence().has_value());
+
+        // Create MockServices.  MockPresenceService::isPresent() should not be
+        // called.
+        MockServices services{};
+        MockPresenceService& presenceService =
+            services.getMockPresenceService();
+        EXPECT_CALL(presenceService, isPresent).Times(0);
+
+        // Execute PresenceDetection
+        EXPECT_FALSE(detection->execute(services, *system, *chassis, *device));
+    }
+
+    // Test where fails
+    {
+        // Clear cached presence value
+        detection->clearCache();
+        EXPECT_FALSE(detection->getCachedPresence().has_value());
+
+        // Create MockServices.  MockPresenceService::isPresent() should throw
+        // an exception.
+        MockServices services{};
+        MockPresenceService& presenceService =
+            services.getMockPresenceService();
+        EXPECT_CALL(presenceService,
+                    isPresent("/xyz/openbmc_project/inventory/system/chassis/"
+                              "motherboard/cpu2"))
+            .Times(1)
+            .WillOnce(
+                Throw(std::runtime_error{"DBusError: Invalid object path."}));
+
+        // Define expected journal messages that should be passed to MockJournal
+        MockJournal& journal = services.getMockJournal();
+        std::vector<std::string> exceptionMessages{
+            "DBusError: Invalid object path.",
+            "ActionError: compare_presence: { fru: "
+            "/xyz/openbmc_project/inventory/system/chassis/motherboard/cpu2, "
+            "value: true }"};
+        EXPECT_CALL(journal, logError(exceptionMessages)).Times(1);
+        EXPECT_CALL(journal,
+                    logError("Unable to determine presence of vdd_reg"))
+            .Times(1);
+
+        // Execute PresenceDetection.  Should return true when an error occurs.
+        EXPECT_TRUE(detection->execute(services, *system, *chassis, *device));
+
+        EXPECT_TRUE(detection->getCachedPresence().has_value());
+        EXPECT_TRUE(detection->getCachedPresence().value());
+    }
 }
 
 TEST(PresenceDetectionTests, GetActions)
@@ -44,13 +267,46 @@
     std::vector<std::unique_ptr<Action>> actions{};
 
     MockAction* action1 = new MockAction{};
-    actions.push_back(std::unique_ptr<MockAction>{action1});
+    actions.emplace_back(std::unique_ptr<MockAction>{action1});
 
     MockAction* action2 = new MockAction{};
-    actions.push_back(std::unique_ptr<MockAction>{action2});
+    actions.emplace_back(std::unique_ptr<MockAction>{action2});
 
-    PresenceDetection presenceDetection(std::move(actions));
-    EXPECT_EQ(presenceDetection.getActions().size(), 2);
-    EXPECT_EQ(presenceDetection.getActions()[0].get(), action1);
-    EXPECT_EQ(presenceDetection.getActions()[1].get(), action2);
+    PresenceDetection detection{std::move(actions)};
+    EXPECT_EQ(detection.getActions().size(), 2);
+    EXPECT_EQ(detection.getActions()[0].get(), action1);
+    EXPECT_EQ(detection.getActions()[1].get(), action2);
+}
+
+TEST(PresenceDetectionTests, GetCachedPresence)
+{
+    // Create MockAction that will return false once
+    std::unique_ptr<MockAction> action = std::make_unique<MockAction>();
+    EXPECT_CALL(*action, execute).Times(1).WillOnce(Return(false));
+
+    // Create PresenceDetection
+    std::vector<std::unique_ptr<Action>> actions{};
+    actions.emplace_back(std::move(action));
+    PresenceDetection* detection = new PresenceDetection(std::move(actions));
+
+    // Create parent System, Chassis, and Device objects
+    auto [system, chassis, device] =
+        createParentObjects(std::unique_ptr<PresenceDetection>{detection});
+
+    // Verify that initially no presence value is cached
+    EXPECT_FALSE(detection->getCachedPresence().has_value());
+
+    // Call execute() which should obtain and cache presence value
+    MockServices services{};
+    EXPECT_FALSE(detection->execute(services, *system, *chassis, *device));
+
+    // Verify false presence value was cached
+    EXPECT_TRUE(detection->getCachedPresence().has_value());
+    EXPECT_FALSE(detection->getCachedPresence().value());
+
+    // Clear cached presence value
+    detection->clearCache();
+
+    // Verify that no presence value is cached
+    EXPECT_FALSE(detection->getCachedPresence().has_value());
 }