diff --git a/App/event.c b/App/event.c
index ba37f39..2247f5f 100644
--- a/App/event.c
+++ b/App/event.c
@@ -196,6 +196,19 @@ void Event_KeyScan_Poll(void)
     u8 raw_sos     = !KEY_SOS; // 恢复 SOS 物理按键电平检测
     key_scan_timer = 0; // 重置扫描分频计数器
 
+    // 【SOS 按键电平实时诊断】
+    {
+        static u8 last_raw_sos = 99;
+        if (raw_sos != last_raw_sos) {
+            last_raw_sos = raw_sos;
+            Uart_SendString("[KEY-DIAG] KEY_SOS (P2.6) logic raw: ");
+            Uart_SendByte(raw_sos ? '1' : '0');
+            Uart_SendString(", Physical GPIO Pin: ");
+            Uart_SendByte(KEY_SOS ? '1' : '0');
+            Uart_SendString("\r\n");
+        }
+    }
+
     // 按键调试诊断：若按键 ADC 值有变化或处于高电平，串口输出真实 ADC 值
     {
         u16 down_val = ADC_ReadFiltered(ADC_CHANNEL_KEY_DOWN);
diff --git a/App/system.c b/App/system.c
index 492e4ed..3b2abbf 100644
--- a/App/system.c
+++ b/App/system.c
@@ -212,6 +212,11 @@ void Self_Test(void)
     Uart_SendByte((u8)('0' + (key_down_adc % 10)));
     Uart_SendString(" [OK]\r\n");
 
+    // 2.2 检测 KEY_SOS (P2.6) 物理电平常态
+    Uart_SendString("[SELF-TEST] KEY_SOS (P2.6) Pin Level: ");
+    Uart_SendByte((u8)(KEY_SOS ? '1' : '0'));
+    Uart_SendString("\r\n");
+
     // 3. 检查 P1.3 电池电压检测与百分比
     vbat_mv = ADC_GetBatteryVoltage_mV();
     percent = ADC_GetBatteryPercent();