diff --git a/components/truma_inetbox/TrumaiNetBoxApp.cpp b/components/truma_inetbox/TrumaiNetBoxApp.cpp
index 832bc2e..9daa059 100644
--- a/components/truma_inetbox/TrumaiNetBoxApp.cpp
+++ b/components/truma_inetbox/TrumaiNetBoxApp.cpp
@@ -33,9 +33,23 @@ void TrumaiNetBoxApp::update() {
   // Master mode auto-discovery (start device discovery once)
   if (this->master_mode_ && !this->master_discovery_started_) {
     this->master_discovery_started_ = true;
-    // Start device discovery for typical Truma heater NAD range
-    this->master_scan_b2(0x7F, 0x00, 0xFF);  // Broadcast scan, full identifier range
-    ESP_LOGI(TAG, "Master mode: Started automatic device discovery");
+    
+    // Start targeted device discovery like CP Plus does
+    // Query known Truma device identifiers instead of full scan
+    
+    // Query identifier 0x23 - typical for Truma heaters
+    std::vector<uint8_t> heater_query = {0xB2, 0x23, 0x17, 0x46, 0x01, 0x03};
+    this->master_send_diag_single(0x7F, heater_query);
+    
+    // Query identifier 0x00 - LIN Product Identification 
+    std::vector<uint8_t> prod_id_query = {0xB2, 0x00, 0x17, 0x46, 0x00, 0x1F};
+    this->master_send_diag_single(0x7F, prod_id_query);
+    
+    // Query identifier 0x00 with different device signatures
+    std::vector<uint8_t> heater_prod_query = {0xB2, 0x00, 0x17, 0x46, 0x40, 0x03}; // Heater signature
+    this->master_send_diag_single(0x7F, heater_prod_query);
+    
+    ESP_LOGI(TAG, "Master mode: Started targeted device discovery (CP Plus style)");
   }
 
     // Master TX scheduler (throttle to ~20ms spacing)