diff --git a/java_console/ui/src/com/rusefi/ui/widgets/ClosedLoopControlQualityMetric.java b/java_console/ui/src/com/rusefi/ui/widgets/ClosedLoopControlQualityMetric.java
index e4373bc526..96fc6cf0c5 100644
--- a/java_console/ui/src/com/rusefi/ui/widgets/ClosedLoopControlQualityMetric.java
+++ b/java_console/ui/src/com/rusefi/ui/widgets/ClosedLoopControlQualityMetric.java
@@ -1,11 +1,12 @@
 package com.rusefi.ui.widgets;
 
+import com.rusefi.CyclicBuffer;
+import com.rusefi.DataBuffer;
 import com.rusefi.core.Sensor;
 import com.rusefi.core.SensorCentral;
 import com.rusefi.core.SensorStats;
 import com.rusefi.core.ValueSource;
 
-import java.util.LinkedList;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
@@ -19,25 +20,24 @@ import java.util.concurrent.TimeUnit;
  * @see SensorStats
  */
 public class ClosedLoopControlQualityMetric {
+    private static final int BUFFER_SIZE = 100;
     private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
 
     private final ValueSource target;
     private final ValueSource result;
     private final Sensor destination;
-    private int maxSize = 100;
 
     /**
-     * Last maxSize number of error measurements
+     * Buffer of recent error measurements
      * GuardedBy(this)
      */
-    private LinkedList<Double> errors = new LinkedList<>();
+    private DataBuffer errors = new CyclicBuffer(BUFFER_SIZE);
 
     /**
      * @param target what value are we trying to achieve
      * @param result what value do we actually have
      */
     public ClosedLoopControlQualityMetric(ValueSource target, ValueSource result, Sensor destination) {
-
         this.target = target;
         this.result = result;
         this.destination = destination;
@@ -56,16 +56,10 @@ public class ClosedLoopControlQualityMetric {
     }
 
     private synchronized double getStandardDeviation() {
-        float sum = 0;
-        for (Double error : errors) {
-            sum += error * error;
-        }
-        return Math.sqrt(sum / errors.size());
+        return DataBuffer.getStandardDeviation(errors.getValues());
     }
 
     private synchronized void rememberCurrentError(double error) {
-        if (errors.size() == maxSize)
-            errors.removeFirst();
         errors.add(error);
     }
 }