diff --git a/sketch/obd2_gauge/meter.h b/sketch/obd2_gauge/meter.h
index d3b298e..38a6a32 100644
--- a/sketch/obd2_gauge/meter.h
+++ b/sketch/obd2_gauge/meter.h
@@ -37,6 +37,11 @@ uint8_t engine_off_count = 0; // counter to indicate engine is off then sleep
 float old_data[maxpidIndex] = {-999, -999, -999, -999}; // keep old data
 float last_valid_data[maxpidIndex] = {-999, -999, -999, -999}; // keep last valid data for instant redraw
 
+// Arc warning flash (blinking alarm when gauge is in TFT_RED)
+bool arcFlashVisible = true;
+uint32_t lastArcFlashTime = 0;
+bool wasInRedAlarm[4] = { false, false, false, false };
+
 // backlight variable average counter
 uint8_t low_count = 0;
 uint8_t high_count = 0;
@@ -818,20 +823,45 @@ void plotArc4(uint8_t cell, float data, int warn, int min, int max, bool digit,
     oldBlocks = NUM_BAR_BLOCKS;
 
   bool colorChanged = (col != oldCol);
-  if (colorChanged || old_data[cell] < min) {
-    for (uint8_t i = 0; i < newBlocks; i++) {
-      drawQuadBarBlock(cell, i, col);
+  if (col == TFT_RED) {
+    wasInRedAlarm[cell] = true;
+    if (colorChanged) {
+      arcFlashVisible = true;
+      lastArcFlashTime = millis();
+      for (uint8_t i = 0; i < newBlocks; i++) {
+        drawQuadBarBlock(cell, i, TFT_RED);
+      }
+      for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+        drawQuadBarBlock(cell, i, TFT_DARKGREY);
+      }
+    } else if (arcFlashVisible) {
+      if (newBlocks > oldBlocks) {
+        for (uint8_t i = oldBlocks; i < newBlocks; i++) {
+          drawQuadBarBlock(cell, i, TFT_RED);
+        }
+      } else if (newBlocks < oldBlocks) {
+        for (uint8_t i = newBlocks; i < oldBlocks; i++) {
+          drawQuadBarBlock(cell, i, TFT_DARKGREY);
+        }
+      }
     }
-    for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
-      drawQuadBarBlock(cell, i, TFT_DARKGREY);
-    }
-  } else if (newBlocks > oldBlocks) {
-    for (uint8_t i = oldBlocks; i < newBlocks; i++) {
-      drawQuadBarBlock(cell, i, col);
-    }
-  } else if (newBlocks < oldBlocks) {
-    for (uint8_t i = newBlocks; i < oldBlocks; i++) {
-      drawQuadBarBlock(cell, i, TFT_DARKGREY);
+  } else {
+    wasInRedAlarm[cell] = false;
+    if (colorChanged || old_data[cell] < min) {
+      for (uint8_t i = 0; i < newBlocks; i++) {
+        drawQuadBarBlock(cell, i, col);
+      }
+      for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+        drawQuadBarBlock(cell, i, TFT_DARKGREY);
+      }
+    } else if (newBlocks > oldBlocks) {
+      for (uint8_t i = oldBlocks; i < newBlocks; i++) {
+        drawQuadBarBlock(cell, i, col);
+      }
+    } else if (newBlocks < oldBlocks) {
+      for (uint8_t i = newBlocks; i < oldBlocks; i++) {
+        drawQuadBarBlock(cell, i, TFT_DARKGREY);
+      }
     }
   }
 
@@ -960,20 +990,45 @@ void plotFullScreen(uint8_t cell, float data, int warn, int min, int max,
       oldBlocks = NUM_BAR_BLOCKS;
 
     bool colorChanged = (col != oldCol);
-    if (colorChanged || old_data[cell] < min) {
-      for (uint8_t i = 0; i < newBlocks; i++) {
-        drawBarBlock(i, col);
+    if (col == TFT_RED) {
+      wasInRedAlarm[cell] = true;
+      if (colorChanged) {
+        arcFlashVisible = true;
+        lastArcFlashTime = millis();
+        for (uint8_t i = 0; i < newBlocks; i++) {
+          drawBarBlock(i, TFT_RED);
+        }
+        for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+          drawBarBlock(i, TFT_DARKGREY);
+        }
+      } else if (arcFlashVisible) {
+        if (newBlocks > oldBlocks) {
+          for (uint8_t i = oldBlocks; i < newBlocks; i++) {
+            drawBarBlock(i, TFT_RED);
+          }
+        } else if (newBlocks < oldBlocks) {
+          for (uint8_t i = newBlocks; i < oldBlocks; i++) {
+            drawBarBlock(i, TFT_DARKGREY);
+          }
+        }
       }
-      for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
-        drawBarBlock(i, TFT_DARKGREY);
-      }
-    } else if (newBlocks > oldBlocks) {
-      for (uint8_t i = oldBlocks; i < newBlocks; i++) {
-        drawBarBlock(i, col);
-      }
-    } else if (newBlocks < oldBlocks) {
-      for (uint8_t i = newBlocks; i < oldBlocks; i++) {
-        drawBarBlock(i, TFT_DARKGREY);
+    } else {
+      wasInRedAlarm[cell] = false;
+      if (colorChanged || old_data[cell] < min) {
+        for (uint8_t i = 0; i < newBlocks; i++) {
+          drawBarBlock(i, col);
+        }
+        for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+          drawBarBlock(i, TFT_DARKGREY);
+        }
+      } else if (newBlocks > oldBlocks) {
+        for (uint8_t i = oldBlocks; i < newBlocks; i++) {
+          drawBarBlock(i, col);
+        }
+      } else if (newBlocks < oldBlocks) {
+        for (uint8_t i = newBlocks; i < oldBlocks; i++) {
+          drawBarBlock(i, TFT_DARKGREY);
+        }
       }
     }
 
@@ -1197,6 +1252,115 @@ void updateMeter(uint8_t pidNo, String response) { // update parameter on screen
 }
 /*-------------------------------*/
 
+// Non-blocking handler to blink/flash arcs on alarm (when in TFT_RED)
+void handleArcAlarmFlash() {
+  uint32_t now = millis();
+  bool toggleTick = false;
+  if (now - lastArcFlashTime >= 250) {
+    lastArcFlashTime = now;
+    arcFlashVisible = !arcFlashVisible;
+    toggleTick = true;
+  }
+
+  if (fullScreenCell >= 0 && fullScreenCell < 4) {
+    uint8_t cell = fullScreenCell;
+    if (!cellIsNumeric[cell] && last_valid_data[cell] != -999) {
+      uint8_t pidIdx = pidInCell[cell];
+      int warn = warningValue[pidIdx].toInt();
+      float data = last_valid_data[cell];
+      uint16_t col = getMeterColor(pidIdx, data, warn);
+      bool inRed = (col == TFT_RED);
+
+      if (wasInRedAlarm[cell] && !inRed) {
+        // Exited red alarm: restore steady arc
+        wasInRedAlarm[cell] = false;
+        int min = pidConfig[pidIdx][4].toInt();
+        int max = pidConfig[pidIdx][5].toInt();
+        int newBlocks = map(data, min, max, 0, NUM_BAR_BLOCKS);
+        if (newBlocks < 0) newBlocks = 0;
+        if (newBlocks > NUM_BAR_BLOCKS) newBlocks = NUM_BAR_BLOCKS;
+        for (uint8_t i = 0; i < newBlocks; i++) {
+          drawBarBlock(i, col);
+        }
+        for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+          drawBarBlock(i, TFT_DARKGREY);
+        }
+      } else if (inRed) {
+        wasInRedAlarm[cell] = true;
+        if (toggleTick) {
+          int min = pidConfig[pidIdx][4].toInt();
+          int max = pidConfig[pidIdx][5].toInt();
+          int newBlocks = map(data, min, max, 0, NUM_BAR_BLOCKS);
+          if (newBlocks < 0) newBlocks = 0;
+          if (newBlocks > NUM_BAR_BLOCKS) newBlocks = NUM_BAR_BLOCKS;
+
+          if (arcFlashVisible) {
+            for (uint8_t i = 0; i < newBlocks; i++) {
+              drawBarBlock(i, TFT_RED);
+            }
+            for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+              drawBarBlock(i, TFT_DARKGREY);
+            }
+          } else {
+            for (uint8_t i = 0; i < NUM_BAR_BLOCKS; i++) {
+              drawBarBlock(i, TFT_BLACK);
+            }
+          }
+        }
+      }
+    }
+  } else {
+    // 4 quadrants mode
+    for (uint8_t cell = 0; cell < 4; cell++) {
+      if (!cellIsNumeric[cell] && last_valid_data[cell] != -999) {
+        uint8_t pidIdx = pidInCell[cell];
+        int warn = warningValue[pidIdx].toInt();
+        float data = last_valid_data[cell];
+        uint16_t col = getMeterColor(pidIdx, data, warn);
+        bool inRed = (col == TFT_RED);
+
+        if (wasInRedAlarm[cell] && !inRed) {
+          // Exited red alarm: restore steady arc
+          wasInRedAlarm[cell] = false;
+          int min = pidConfig[pidIdx][4].toInt();
+          int max = pidConfig[pidIdx][5].toInt();
+          int newBlocks = map(data, min, max, 0, NUM_BAR_BLOCKS);
+          if (newBlocks < 0) newBlocks = 0;
+          if (newBlocks > NUM_BAR_BLOCKS) newBlocks = NUM_BAR_BLOCKS;
+          for (uint8_t i = 0; i < newBlocks; i++) {
+            drawQuadBarBlock(cell, i, col);
+          }
+          for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+            drawQuadBarBlock(cell, i, TFT_DARKGREY);
+          }
+        } else if (inRed) {
+          wasInRedAlarm[cell] = true;
+          if (toggleTick) {
+            int min = pidConfig[pidIdx][4].toInt();
+            int max = pidConfig[pidIdx][5].toInt();
+            int newBlocks = map(data, min, max, 0, NUM_BAR_BLOCKS);
+            if (newBlocks < 0) newBlocks = 0;
+            if (newBlocks > NUM_BAR_BLOCKS) newBlocks = NUM_BAR_BLOCKS;
+
+            if (arcFlashVisible) {
+              for (uint8_t i = 0; i < newBlocks; i++) {
+                drawQuadBarBlock(cell, i, TFT_RED);
+              }
+              for (uint8_t i = newBlocks; i < NUM_BAR_BLOCKS; i++) {
+                drawQuadBarBlock(cell, i, TFT_DARKGREY);
+              }
+            } else {
+              for (uint8_t i = 0; i < NUM_BAR_BLOCKS; i++) {
+                drawQuadBarBlock(cell, i, TFT_BLACK);
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
+
 // Target and current brightness variables for smooth fade
 uint8_t targetBacklight = 255;
 float currentBacklight = 255.0f;
diff --git a/sketch/obd2_gauge/obd2_gauge.ino b/sketch/obd2_gauge/obd2_gauge.ino
index 432de8a..e99b482 100644
--- a/sketch/obd2_gauge/obd2_gauge.ino
+++ b/sketch/obd2_gauge/obd2_gauge.ino
@@ -335,7 +335,8 @@ recent_client_addr : {0x00,0x00,0x00,0x00,0x00,0x00} array of bytes[6]
 
 /*###################################*/
 void loop() {
-  updateBacklightFade(); // non-blocking smooth backlight fade handler
+  updateBacklightFade();  // non-blocking smooth backlight fade handler
+  handleArcAlarmFlash();  // non-blocking arc alarm flash handler (blinks when in TFT_RED)
 
   // SCAN TOUCHSCREEN
   // - Single click on a quadrant: toggles between clock (arc) and number