diff --git a/html/assets/js/selftest.js b/html/assets/js/selftest.js
index fe96879..52b02af 100644
--- a/html/assets/js/selftest.js
+++ b/html/assets/js/selftest.js
@@ -336,21 +336,27 @@ async function selfTestSequence() {
           addSelfTestLog(`NPM response: PM1=${npmResult.PM1}, PM2.5=${npmResult.PM25}, PM10=${npmResult.PM10}, status=${npmResult.npm_status_hex}`);
 
           // Decode npm_status flags
-          const status = npmResult.npm_status || 0;
-          const statusFlags = {
-            0x01: "Sleep mode",
-            0x02: "Degraded mode",
-            0x04: "Not ready",
-            0x08: "Heater error",
-            0x10: "THP sensor error",
-            0x20: "Fan error",
-            0x40: "Memory error",
-            0x80: "Laser error"
-          };
-          const activeErrors = [];
-          Object.entries(statusFlags).forEach(([mask, label]) => {
-            if (status & mask) activeErrors.push(label);
-          });
+          const status = npmResult.npm_status !== undefined ? npmResult.npm_status : 0;
+
+          if (status === 0xFF) {
+            // 0xFF = no response = disconnected
+            updateTestStatus(sensor.id, 'Failed', 'Capteur déconnecté', 'bg-danger');
+            testsFailed++;
+          } else {
+            const statusFlags = {
+              0x01: "Sleep mode",
+              0x02: "Degraded mode",
+              0x04: "Not ready",
+              0x08: "Heater error",
+              0x10: "THP sensor error",
+              0x20: "Fan error",
+              0x40: "Memory error",
+              0x80: "Laser error"
+            };
+            const activeErrors = [];
+            Object.entries(statusFlags).forEach(([mask, label]) => {
+              if (status & mask) activeErrors.push(label);
+            });
 
           if (activeErrors.length > 0) {
             updateTestStatus(sensor.id, 'Warning', `Status ${npmResult.npm_status_hex}: ${activeErrors.join(', ')}`, 'bg-warning');
@@ -362,6 +368,7 @@ async function selfTestSequence() {
             updateTestStatus(sensor.id, 'Warning', 'Incomplete data received', 'bg-warning');
             testsFailed++;
           }
+          } // end else (not 0xFF)
 
         } else if (sensor.type === 'BME280') {
           // BME280 sensor test
diff --git a/html/sensors.html b/html/sensors.html
index 1d0367f..b45044f 100755
--- a/html/sensors.html
+++ b/html/sensors.html
@@ -155,36 +155,51 @@
           // NPM status decoded
           if (response.npm_status !== undefined) {
             const status = response.npm_status;
-            const statusText = status === 0 ? "OK" : response.npm_status_hex;
-            const statusColor = status === 0 ? "green" : "orange";
-            $("#data-table-body_" + port).append(`
-              <tr>
-                <td>Status</td>
-                <td style="color: ${statusColor}; font-weight: bold;">${statusText}</td>
-              </tr>
-            `);
 
-            // Decode individual error bits
-            const statusFlags = {
-              0x01: "Sleep mode",
-              0x02: "Degraded mode",
-              0x04: "Not ready",
-              0x08: "Heater error",
-              0x10: "THP sensor error",
-              0x20: "Fan error",
-              0x40: "Memory error",
-              0x80: "Laser error"
-            };
-            Object.entries(statusFlags).forEach(([mask, label]) => {
-              if (status & mask) {
-                $("#data-table-body_" + port).append(`
-                  <tr class="error-row">
-                    <td></td>
-                    <td style="color: red;">⚠ ${label}</td>
-                  </tr>
-                `);
-              }
-            });
+            if (status === 0xFF) {
+              // 0xFF = no response from sensor = disconnected
+              $("#data-table-body_" + port).append(`
+                <tr>
+                  <td>Status</td>
+                  <td style="color: red; font-weight: bold;">Capteur déconnecté</td>
+                </tr>
+              `);
+            } else if (status === 0) {
+              $("#data-table-body_" + port).append(`
+                <tr>
+                  <td>Status</td>
+                  <td style="color: green; font-weight: bold;">OK</td>
+                </tr>
+              `);
+            } else {
+              $("#data-table-body_" + port).append(`
+                <tr>
+                  <td>Status</td>
+                  <td style="color: orange; font-weight: bold;">${response.npm_status_hex}</td>
+                </tr>
+              `);
+              // Decode individual error bits
+              const statusFlags = {
+                0x01: "Sleep mode",
+                0x02: "Degraded mode",
+                0x04: "Not ready",
+                0x08: "Heater error",
+                0x10: "THP sensor error",
+                0x20: "Fan error",
+                0x40: "Memory error",
+                0x80: "Laser error"
+              };
+              Object.entries(statusFlags).forEach(([mask, label]) => {
+                if (status & mask) {
+                  $("#data-table-body_" + port).append(`
+                    <tr class="error-row">
+                      <td></td>
+                      <td style="color: red;">⚠ ${label}</td>
+                    </tr>
+                  `);
+                }
+              });
+            }
           }
         },
         error: function (xhr, status, error) {