diff --git a/frontend/src/pages/onboarding.tsx b/frontend/src/pages/onboarding.tsx
index 4b43f0fb..d6db140a 100644
--- a/frontend/src/pages/onboarding.tsx
+++ b/frontend/src/pages/onboarding.tsx
@@ -100,30 +100,84 @@ const OnboardingPage = () => {
     }
   ];
 
-  // Mock WebSocket for training progress
   useEffect(() => {
-    if (formData.trainingTaskId && currentStep === 4) {
-      const interval = setInterval(async () => {
+    const startTrainingWhenReachingStep4 = async () => {
+      // Only trigger if we just reached step 4 and haven't started training yet
+      if (currentStep === 4 && !formData.trainingTaskId && !loading) {
+        console.log('Auto-starting training for step 4...');
+        
+        setLoading(true);
+        
         try {
-          const status = await api.training.getTrainingStatus(formData.trainingTaskId);
-          setTrainingProgress(status);
-          
-          if (status.status === 'completed') {
-            setCompletedSteps([...completedSteps, 4]);
-            clearInterval(interval);
-            showNotification('success', '¡Entrenamiento completado!', 'Los modelos están listos para usar.');
-          } else if (status.status === 'failed') {
-            clearInterval(interval);
-            showNotification('error', 'Error en entrenamiento', 'Hubo un problema durante el entrenamiento.');
+          // Check if we have required data
+          if (!formData.selected_products || formData.selected_products.length === 0) {
+            showNotification('error', 'No hay productos', 'No se han seleccionado productos para entrenar.');
+            setLoading(false);
+            return;
           }
+          
+          if (!currentTenantId) {
+            showNotification('error', 'Error de configuración', 'No se ha configurado el tenant ID.');
+            setLoading(false);
+            return;
+          }
+          
+          // Training configuration
+          const trainingConfig = {
+            include_weather: true,
+            include_traffic: true,
+            products: formData.selected_products,
+            min_data_points: 30,
+            forecast_horizon_days: 7,
+            cross_validation_folds: 3,
+            hyperparameter_tuning: true
+          };
+          
+          console.log('Starting training with config:', trainingConfig);
+          
+          // Start training via API
+          const trainingJob = await api.training.startTraining(trainingConfig);
+          
+          // Update form data with training job ID
+          setFormData(prev => ({ 
+            ...prev, 
+            trainingTaskId: trainingJob.id,
+            trainingStatus: 'running' 
+          }));
+          
+          showNotification('info', 'Entrenamiento iniciado', 'Los modelos se están entrenando...');
+          
         } catch (error) {
-          console.error('Error fetching training status:', error);
+          console.error('Error starting training:', error);
+          
+          let errorMessage = 'No se pudo iniciar el entrenamiento.';
+          let errorTitle = 'Error de entrenamiento';
+          
+          if (error.response?.status === 400) {
+            errorMessage = error.response.data?.detail || 'Configuración de entrenamiento inválida.';
+          } else if (error.response?.status === 401) {
+            errorMessage = 'No autorizado. Por favor, inicia sesión nuevamente.';
+            errorTitle = 'Error de autenticación';
+          } else if (error.response?.status === 403) {
+            errorMessage = 'No tienes permisos para iniciar el entrenamiento.';
+            errorTitle = 'Error de permisos';
+          } else if (error.response?.status === 500) {
+            errorMessage = 'Error interno del servidor. Inténtalo más tarde.';
+            errorTitle = 'Error del servidor';
+          }
+          
+          showNotification('error', errorTitle, errorMessage);
+          
+          // Optionally go back to previous step on error
+          // setCurrentStep(3);
+        } finally {
+          setLoading(false);
         }
-      }, 2000);
-
-      return () => clearInterval(interval);
-    }
-  }, [formData.trainingTaskId, currentStep]);
+      }
+    };
+    
+    startTrainingWhenReachingStep4();
+  }, [currentStep, formData.trainingTaskId, formData.selected_products, currentTenantId, loading]);
 
   const showNotification = (type, title, message) => {
     const id = Date.now().toString();