diff --git a/pid/pidcontroller.hpp b/pid/pidcontroller.hpp
index cb92377..c3bbc2e 100644
--- a/pid/pidcontroller.hpp
+++ b/pid/pidcontroller.hpp
@@ -21,7 +21,7 @@
 {
   public:
     PIDController(const std::string& id, ZoneInterface* owner) :
-        Controller(), _owner(owner), _setpoint(0), _id(id)
+        Controller(), _owner(owner), _id(id)
     {}
 
     virtual ~PIDController()
@@ -58,12 +58,12 @@
 
   protected:
     ZoneInterface* _owner;
+    std::string _id;
 
   private:
     // parameters
     ec::pid_info_t _pid_info;
-    double _setpoint;
-    std::string _id;
+    double _setpoint = 0;
     double lastInput = std::numeric_limits<double>::quiet_NaN();
 };
 
diff --git a/pid/stepwisecontroller.cpp b/pid/stepwisecontroller.cpp
index c8ec219..5c36778 100644
--- a/pid/stepwisecontroller.cpp
+++ b/pid/stepwisecontroller.cpp
@@ -101,7 +101,7 @@
     }
     else
     {
-        _owner->addSetPoint(value);
+        _owner->addSetPoint(value, _id);
     }
     return;
 }
diff --git a/pid/thermalcontroller.cpp b/pid/thermalcontroller.cpp
index 8125349..71374a1 100644
--- a/pid/thermalcontroller.cpp
+++ b/pid/thermalcontroller.cpp
@@ -123,7 +123,7 @@
 // bmc_set_pid_output
 void ThermalController::outputProc(double value)
 {
-    _owner->addSetPoint(value);
+    _owner->addSetPoint(value, _id);
 
     return;
 }
diff --git a/pid/zone.cpp b/pid/zone.cpp
index af40a2b..1eda992 100644
--- a/pid/zone.cpp
+++ b/pid/zone.cpp
@@ -101,9 +101,18 @@
     return _zoneId;
 }
 
-void DbusPidZone::addSetPoint(double setpoint)
+void DbusPidZone::addSetPoint(double setPoint, const std::string& name)
 {
-    _SetPoints.push_back(setpoint);
+    _SetPoints.push_back(setPoint);
+    /*
+     * if there are multiple thermal controllers with the same
+     * value, pick the first one in the iterator
+     */
+    if (_maximumSetPoint < setPoint)
+    {
+        _maximumSetPoint = setPoint;
+        _maximumSetPointName = name;
+    }
 }
 
 void DbusPidZone::addRPMCeiling(double ceiling)
@@ -119,6 +128,7 @@
 void DbusPidZone::clearSetPoints(void)
 {
     _SetPoints.clear();
+    _maximumSetPoint = 0;
 }
 
 double DbusPidZone::getFailSafePercent(void) const
@@ -126,7 +136,7 @@
     return _failSafePercent;
 }
 
-double DbusPidZone::getMinThermalSetpoint(void) const
+double DbusPidZone::getMinThermalSetPoint(void) const
 {
     return _minThermalOutputSetPt;
 }
@@ -210,27 +220,46 @@
 
 void DbusPidZone::determineMaxSetPointRequest(void)
 {
-    double max = 0;
     std::vector<double>::iterator result;
-
-    if (_SetPoints.size() > 0)
-    {
-        result = std::max_element(_SetPoints.begin(), _SetPoints.end());
-        max = *result;
-    }
+    double minThermalThreshold = getMinThermalSetPoint();
 
     if (_RPMCeilings.size() > 0)
     {
         result = std::min_element(_RPMCeilings.begin(), _RPMCeilings.end());
-        max = std::min(max, *result);
+        // if Max set point is larger than the lowest ceiling, reset to lowest
+        // ceiling.
+        if (*result < _maximumSetPoint)
+        {
+            _maximumSetPoint = *result;
+            // When using lowest ceiling, controller name is ceiling.
+            _maximumSetPointName = "Ceiling";
+        }
     }
 
     /*
      * If the maximum RPM setpoint output is below the minimum RPM
      * setpoint, set it to the minimum.
      */
-    max = std::max(getMinThermalSetpoint(), max);
-
+    if (minThermalThreshold >= _maximumSetPoint)
+    {
+        _maximumSetPoint = minThermalThreshold;
+        _maximumSetPointName = "";
+    }
+    else if (_maximumSetPointName.compare(_maximumSetPointNamePrev))
+    {
+        std::cerr << "PID Zone " << _zoneId << " max SetPoint "
+                  << _maximumSetPoint << " requested by "
+                  << _maximumSetPointName;
+        for (const auto& sensor : _failSafeSensors)
+        {
+            if (sensor.find("Fan") == std::string::npos)
+            {
+                std::cerr << " " << sensor;
+            }
+        }
+        std::cerr << "\n";
+        _maximumSetPointNamePrev.assign(_maximumSetPointName);
+    }
     if (tuningEnabled)
     {
         /*
@@ -240,17 +269,15 @@
          */
         static constexpr auto setpointpath = "/etc/thermal.d/setpoint";
 
-        fileParseRpm(setpointpath, max);
+        fileParseRpm(setpointpath, _maximumSetPoint);
 
         // Allow per-zone setpoint files to override overall setpoint file
         std::ostringstream zoneSuffix;
         zoneSuffix << ".zone" << _zoneId;
         std::string zoneSetpointPath = setpointpath + zoneSuffix.str();
 
-        fileParseRpm(zoneSetpointPath, max);
+        fileParseRpm(zoneSetpointPath, _maximumSetPoint);
     }
-
-    _maximumSetPoint = max;
     return;
 }
 
@@ -260,7 +287,7 @@
      * epoch_ms,setpt,fan1,fan2,fanN,sensor1,sensor2,sensorN,failsafe
      */
 
-    _log << "epoch_ms,setpt";
+    _log << "epoch_ms,setpt,requester";
 
     for (const auto& f : _fanInputs)
     {
@@ -308,6 +335,7 @@
                     now.time_since_epoch())
                     .count();
         _log << "," << _maximumSetPoint;
+        _log << "," << _maximumSetPointName;
     }
 
     for (const auto& f : _fanInputs)
diff --git a/pid/zone.hpp b/pid/zone.hpp
index 01dc62e..c73ad39 100644
--- a/pid/zone.hpp
+++ b/pid/zone.hpp
@@ -61,13 +61,13 @@
     bool getFailSafeMode(void) const override;
 
     int64_t getZoneID(void) const;
-    void addSetPoint(double setpoint) override;
+    void addSetPoint(double setPoint, const std::string& name) override;
     double getMaxSetPointRequest(void) const override;
     void addRPMCeiling(double ceiling) override;
     void clearSetPoints(void) override;
     void clearRPMCeilings(void) override;
     double getFailSafePercent(void) const override;
-    double getMinThermalSetpoint(void) const;
+    double getMinThermalSetPoint(void) const;
 
     Sensor* getSensor(const std::string& name) override;
     void determineMaxSetPointRequest(void) override;
@@ -98,6 +98,8 @@
 
     const int64_t _zoneId;
     double _maximumSetPoint = 0;
+    std::string _maximumSetPointName;
+    std::string _maximumSetPointNamePrev;
     bool _manualMode = false;
     bool _redundantWrite = false;
     const double _minThermalOutputSetPt;
diff --git a/pid/zone_interface.hpp b/pid/zone_interface.hpp
index b8da048..982e051 100644
--- a/pid/zone_interface.hpp
+++ b/pid/zone_interface.hpp
@@ -46,7 +46,7 @@
     virtual double getCachedValue(const std::string& name) = 0;
 
     /** Add a set point value for the Max Set Point computation. */
-    virtual void addSetPoint(double setpoint) = 0;
+    virtual void addSetPoint(double setpoint, const std::string& name) = 0;
     /** Clear all set points specified via addSetPoint */
     virtual void clearSetPoints(void) = 0;
 
diff --git a/test/pid_stepwisecontroller_unittest.cpp b/test/pid_stepwisecontroller_unittest.cpp
index d9a7728..a832ed7 100644
--- a/test/pid_stepwisecontroller_unittest.cpp
+++ b/test/pid_stepwisecontroller_unittest.cpp
@@ -44,8 +44,8 @@
         .WillOnce(Return(31.0))  // return 40
         .WillOnce(Return(32.0)); // return 60
 
-    EXPECT_CALL(z, addSetPoint(40.0)).Times(2);
-    EXPECT_CALL(z, addSetPoint(60.0)).Times(1);
+    EXPECT_CALL(z, addSetPoint(40.0, "foo")).Times(2);
+    EXPECT_CALL(z, addSetPoint(60.0, "foo")).Times(1);
 
     for (int ii = 0; ii < 3; ii++)
     {
@@ -80,8 +80,8 @@
         .WillOnce(Return(27.0))  // return 60
         .WillOnce(Return(26.0)); // return 40
 
-    EXPECT_CALL(z, addSetPoint(40.0)).Times(1);
-    EXPECT_CALL(z, addSetPoint(60.0)).Times(2);
+    EXPECT_CALL(z, addSetPoint(40.0, "foo")).Times(1);
+    EXPECT_CALL(z, addSetPoint(60.0, "foo")).Times(2);
 
     for (int ii = 0; ii < 3; ii++)
     {
diff --git a/test/pid_thermalcontroller_unittest.cpp b/test/pid_thermalcontroller_unittest.cpp
index ef4de66..57a1b9f 100644
--- a/test/pid_thermalcontroller_unittest.cpp
+++ b/test/pid_thermalcontroller_unittest.cpp
@@ -104,7 +104,7 @@
     EXPECT_FALSE(p == nullptr);
 
     double value = 90.0;
-    EXPECT_CALL(z, addSetPoint(value));
+    EXPECT_CALL(z, addSetPoint(value, "therm1"));
 
     p->outputProc(value);
 }
@@ -175,7 +175,7 @@
         .WillOnce(Return(9.0))
         .WillOnce(Return(7.0));
 
-    EXPECT_CALL(z, addSetPoint(_)).Times(3);
+    EXPECT_CALL(z, addSetPoint(_, "therm1")).Times(3);
 
     std::vector<double> lastReadings = {12.0, 12.0, 7.0};
     for (auto& reading : lastReadings)
@@ -208,7 +208,7 @@
         .WillOnce(Return(13.0))
         .WillOnce(Return(14.0));
 
-    EXPECT_CALL(z, addSetPoint(_)).Times(3);
+    EXPECT_CALL(z, addSetPoint(_, "therm1")).Times(3);
 
     std::vector<double> lastReadings = {8.0, 8.0, 14.0};
     for (auto& reading : lastReadings)
diff --git a/test/pid_zone_unittest.cpp b/test/pid_zone_unittest.cpp
index 90d2a2f..172c818 100644
--- a/test/pid_zone_unittest.cpp
+++ b/test/pid_zone_unittest.cpp
@@ -161,14 +161,14 @@
 TEST_F(PidZoneTest, RpmSetPoints_AddMaxClear_BehaveAsExpected)
 {
     // Tests addSetPoint, clearSetPoints, determineMaxSetPointRequest
-    // and getMinThermalSetpoint.
+    // and getMinThermalSetPoint.
 
     // At least one value must be above the minimum thermal setpoint used in
     // the constructor otherwise it'll choose that value
     std::vector<double> values = {100, 200, 300, 400, 500, 5000};
     for (auto v : values)
     {
-        zone->addSetPoint(v);
+        zone->addSetPoint(v, "");
     }
 
     // This will pull the maximum RPM setpoint request.
@@ -180,7 +180,7 @@
 
     // This will go through the RPM set point values and grab the maximum.
     zone->determineMaxSetPointRequest();
-    EXPECT_EQ(zone->getMinThermalSetpoint(), zone->getMaxSetPointRequest());
+    EXPECT_EQ(zone->getMinThermalSetPoint(), zone->getMaxSetPointRequest());
 }
 
 TEST_F(PidZoneTest, RpmSetPoints_AddBelowMinimum_BehavesAsExpected)
@@ -191,14 +191,14 @@
     std::vector<double> values = {100, 200, 300, 400, 500};
     for (auto v : values)
     {
-        zone->addSetPoint(v);
+        zone->addSetPoint(v, "");
     }
 
     // This will pull the maximum RPM setpoint request.
     zone->determineMaxSetPointRequest();
 
     // Verifies the value returned in the minimal thermal rpm set point.
-    EXPECT_EQ(zone->getMinThermalSetpoint(), zone->getMaxSetPointRequest());
+    EXPECT_EQ(zone->getMinThermalSetPoint(), zone->getMaxSetPointRequest());
 }
 
 TEST_F(PidZoneTest, GetFailSafePercent_ReturnsExpected)
diff --git a/test/zone_mock.hpp b/test/zone_mock.hpp
index bab77e3..dd98c15 100644
--- a/test/zone_mock.hpp
+++ b/test/zone_mock.hpp
@@ -19,7 +19,7 @@
     MOCK_METHOD0(initializeCache, void());
     MOCK_METHOD1(getCachedValue, double(const std::string&));
     MOCK_CONST_METHOD0(getRedundantWrite, bool(void));
-    MOCK_METHOD1(addSetPoint, void(double));
+    MOCK_METHOD2(addSetPoint, void(double, const std::string&));
     MOCK_METHOD0(clearSetPoints, void());
     MOCK_METHOD1(addRPMCeiling, void(double));
     MOCK_METHOD0(clearRPMCeilings, void());