diff --git a/phosphor-regulators/src/phase_fault_detection.cpp b/phosphor-regulators/src/phase_fault_detection.cpp
new file mode 100644
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--- /dev/null
+++ b/phosphor-regulators/src/phase_fault_detection.cpp
@@ -0,0 +1,144 @@
+/**
+ * Copyright © 2021 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 "phase_fault_detection.hpp"
+
+#include "action_utils.hpp"
+#include "chassis.hpp"
+#include "device.hpp"
+#include "error_logging.hpp"
+#include "error_logging_utils.hpp"
+#include "exception_utils.hpp"
+#include "journal.hpp"
+#include "system.hpp"
+
+#include <exception>
+#include <map>
+
+namespace phosphor::power::regulators
+{
+
+/**
+ * Maximum number of action errors to write to the journal.
+ */
+constexpr unsigned short maxActionErrorCount{3};
+
+/**
+ * Number of consecutive phase faults required to log an error.  This provides
+ * "de-glitching" to ignore transient hardware problems.
+ */
+constexpr unsigned short requiredConsecutiveFaults{2};
+
+void PhaseFaultDetection::execute(Services& services, System& system,
+                                  Chassis& /*chassis*/, Device& regulator)
+{
+    try
+    {
+        // Find the device ID to use.  If the deviceID data member is empty, use
+        // the ID of the specified regulator.
+        const std::string& effectiveDeviceID =
+            deviceID.empty() ? regulator.getID() : deviceID;
+
+        // Create ActionEnvironment
+        ActionEnvironment environment{system.getIDMap(), effectiveDeviceID,
+                                      services};
+
+        // Execute the actions to detect phase faults
+        action_utils::execute(actions, environment);
+
+        // Check for any N or N+1 phase faults that were detected
+        checkForPhaseFault(PhaseFaultType::n, services, regulator, environment);
+        checkForPhaseFault(PhaseFaultType::n_plus_1, services, regulator,
+                           environment);
+    }
+    catch (const std::exception& e)
+    {
+        // Log error messages in journal if we haven't hit the max
+        if (actionErrorCount < maxActionErrorCount)
+        {
+            ++actionErrorCount;
+            services.getJournal().logError(exception_utils::getMessages(e));
+            services.getJournal().logError(
+                "Unable to detect phase faults in regulator " +
+                regulator.getID());
+        }
+
+        // Create error log entry if this type hasn't already been logged
+        error_logging_utils::logError(std::current_exception(),
+                                      Entry::Level::Warning, services,
+                                      errorHistory);
+    }
+}
+
+void PhaseFaultDetection::checkForPhaseFault(PhaseFaultType faultType,
+                                             Services& services,
+                                             Device& regulator,
+                                             ActionEnvironment& environment)
+{
+    // Find ErrorType that corresponds to PhaseFaultType; used by ErrorHistory
+    ErrorType errorType = toErrorType(faultType);
+
+    // If this error has not been logged yet
+    if (!errorHistory.wasLogged(errorType))
+    {
+        // Create reference to consecutive fault count data member
+        unsigned short& faultCount =
+            (faultType == PhaseFaultType::n) ? nFaultCount : nPlus1FaultCount;
+
+        // Check if the phase fault was detected
+        if (environment.getPhaseFaults().count(faultType) == 0)
+        {
+            // Phase fault not detected; reset consecutive fault count
+            faultCount = 0;
+        }
+        else
+        {
+            // Phase fault detected; increment consecutive fault count
+            ++faultCount;
+
+            // Log error message in journal
+            services.getJournal().logError(
+                toString(faultType) + " phase fault detected in regulator " +
+                regulator.getID() + ": count=" + std::to_string(faultCount));
+
+            // If the required number of consecutive faults have been detected
+            if (faultCount >= requiredConsecutiveFaults)
+            {
+                // Log phase fault error and update ErrorHistory
+                logPhaseFault(faultType, services, regulator, environment);
+                errorHistory.setWasLogged(errorType, true);
+            }
+        }
+    }
+}
+
+void PhaseFaultDetection::logPhaseFault(PhaseFaultType faultType,
+                                        Services& services, Device& regulator,
+                                        ActionEnvironment& environment)
+{
+    ErrorLogging& errorLogging = services.getErrorLogging();
+    Entry::Level severity = (faultType == PhaseFaultType::n)
+                                ? Entry::Level::Warning
+                                : Entry::Level::Informational;
+    Journal& journal = services.getJournal();
+    const std::string& inventoryPath = regulator.getFRU();
+    const std::map<std::string, std::string>& additionalData =
+        environment.getAdditionalErrorData();
+    errorLogging.logPhaseFault(severity, journal, faultType, inventoryPath,
+                               additionalData);
+}
+
+} // namespace phosphor::power::regulators