diff --git a/src/screens/AIChatScreen.tsx b/src/screens/AIChatScreen.tsx
index 6f49d0bc..a669bb5c 100644
--- a/src/screens/AIChatScreen.tsx
+++ b/src/screens/AIChatScreen.tsx
@@ -696,8 +696,14 @@ const AIChatScreen: React.FC = () => {
       if (error instanceof Error) {
         if (error.message.includes('not configured')) {
           errorMessage = 'Please configure your OpenRouter API key in Settings > AI Assistant.';
+        } else if (/401|unauthorized|invalid api key|authentication/i.test(error.message)) {
+          errorMessage = 'OpenRouter rejected your API key. Please verify the key in Settings > AI Assistant.';
+        } else if (/insufficient|credit|quota|429/i.test(error.message)) {
+          errorMessage = 'OpenRouter quota/credits were rejected for this request. Please check your OpenRouter usage and limits.';
+        } else if (/model|provider|endpoint|unsupported|unavailable|not found/i.test(error.message)) {
+          errorMessage = 'The selected OpenRouter model is unavailable. Retry with `openrouter/free` or choose another custom model in Settings > AI Assistant.';
         } else if (error.message.includes('API request failed')) {
-          errorMessage = 'Failed to connect to AI service. Please check your internet connection and API key.';
+          errorMessage = 'Failed to connect to AI service. Please check your internet connection, API key, and OpenRouter model availability.';
         }
       }
 
diff --git a/src/screens/AISettingsScreen.tsx b/src/screens/AISettingsScreen.tsx
index 251134af..3d88b2a4 100644
--- a/src/screens/AISettingsScreen.tsx
+++ b/src/screens/AISettingsScreen.tsx
@@ -25,6 +25,7 @@ import { useTranslation } from 'react-i18next';
 
 const { width } = Dimensions.get('window');
 const isTablet = width >= 768;
+const DEFAULT_OPENROUTER_MODEL = 'openrouter/free';
 
 const AISettingsScreen: React.FC = () => {
   const { t } = useTranslation();
@@ -75,6 +76,8 @@ const AISettingsScreen: React.FC = () => {
   const [apiKey, setApiKey] = useState('');
   const [loading, setLoading] = useState(false);
   const [isKeySet, setIsKeySet] = useState(false);
+  const [useDefaultModel, setUseDefaultModel] = useState(true);
+  const [customModel, setCustomModel] = useState('');
 
   useEffect(() => {
     loadApiKey();
@@ -82,11 +85,21 @@ const AISettingsScreen: React.FC = () => {
 
   const loadApiKey = async () => {
     try {
-      const savedKey = await mmkvStorage.getItem('openrouter_api_key');
+      const [savedKey, savedModel] = await Promise.all([
+        mmkvStorage.getItem('openrouter_api_key'),
+        mmkvStorage.getItem('openrouter_model'),
+      ]);
       if (savedKey) {
         setApiKey(savedKey);
         setIsKeySet(true);
       }
+      if (savedModel && savedModel.trim()) {
+        setUseDefaultModel(false);
+        setCustomModel(savedModel.trim());
+      } else {
+        setUseDefaultModel(true);
+        setCustomModel('');
+      }
     } catch (error) {
       if (__DEV__) console.error('Error loading OpenRouter API key:', error);
     }
@@ -106,6 +119,11 @@ const AISettingsScreen: React.FC = () => {
     setLoading(true);
     try {
       await mmkvStorage.setItem('openrouter_api_key', apiKey.trim());
+      if (useDefaultModel || !customModel.trim()) {
+        await mmkvStorage.removeItem('openrouter_model');
+      } else {
+        await mmkvStorage.setItem('openrouter_model', customModel.trim());
+      }
       setIsKeySet(true);
       openAlert(t('common.success'), t('ai_settings.success_saved'));
     } catch (error) {
@@ -253,6 +271,44 @@ const AISettingsScreen: React.FC = () => {
               autoCorrect={false}
             />
 
+            <View style={styles.modelSection}>
+              <View style={styles.modelHeader}>
+                <Text style={[styles.label, { color: currentTheme.colors.highEmphasis }]}>
+                  Model
+                </Text>
+                <Switch
+                  value={useDefaultModel}
+                  onValueChange={setUseDefaultModel}
+                  trackColor={{ false: currentTheme.colors.elevation2, true: currentTheme.colors.primary }}
+                  thumbColor={useDefaultModel ? currentTheme.colors.white : currentTheme.colors.mediumEmphasis}
+                  ios_backgroundColor={currentTheme.colors.elevation2}
+                />
+              </View>
+              <Text style={[styles.description, { color: currentTheme.colors.mediumEmphasis }]}>
+                {useDefaultModel
+                  ? `Using ${DEFAULT_OPENROUTER_MODEL} (free automatic routing).`
+                  : 'Use a custom OpenRouter model ID (useful for paid plans).'}
+              </Text>
+              {!useDefaultModel && (
+                <TextInput
+                  style={[
+                    styles.input,
+                    {
+                      backgroundColor: currentTheme.colors.elevation2,
+                      color: currentTheme.colors.highEmphasis,
+                      borderColor: currentTheme.colors.elevation2
+                    }
+                  ]}
+                  value={customModel}
+                  onChangeText={setCustomModel}
+                  placeholder="e.g. openai/gpt-4o-mini"
+                  placeholderTextColor={currentTheme.colors.mediumEmphasis}
+                  autoCapitalize="none"
+                  autoCorrect={false}
+                />
+              )}
+            </View>
+
             <View style={styles.buttonContainer}>
               {!isKeySet ? (
                 <TouchableOpacity
@@ -468,6 +524,15 @@ const styles = StyleSheet.create({
   apiKeySection: {
     gap: 12,
   },
+  modelSection: {
+    gap: 8,
+    marginTop: 4,
+  },
+  modelHeader: {
+    flexDirection: 'row',
+    alignItems: 'center',
+    justifyContent: 'space-between',
+  },
   label: {
     fontSize: 16,
     fontWeight: '600',
diff --git a/src/services/aiService.ts b/src/services/aiService.ts
index 8265045f..7c773a05 100644
--- a/src/services/aiService.ts
+++ b/src/services/aiService.ts
@@ -126,10 +126,18 @@ interface OpenRouterResponse {
   };
 }
 
+interface OpenRouterErrorResponse {
+  error?: {
+    message?: string;
+    code?: string;
+  };
+}
+
 class AIService {
   private static instance: AIService;
   private apiKey: string | null = null;
   private baseUrl = 'https://openrouter.ai/api/v1';
+  private defaultModel = 'openrouter/free';
 
   private constructor() { }
 
@@ -151,12 +159,41 @@ class AIService {
   }
 
   async isConfigured(): Promise<boolean> {
-    if (!this.apiKey) {
-      await this.initialize();
-    }
+    // Always refresh from storage so key changes in settings are picked up immediately.
+    await this.initialize();
     return !!this.apiKey;
   }
 
+  private async getPreferredModels(): Promise<string[]> {
+    const configuredModel = (await mmkvStorage.getItem('openrouter_model'))?.trim();
+    if (!configuredModel) {
+      return [this.defaultModel];
+    }
+    return [configuredModel];
+  }
+
+  private async parseErrorResponse(response: Response): Promise<{
+    statusLine: string;
+    message: string;
+    raw: string;
+  }> {
+    const raw = await response.text();
+    let message = '';
+
+    try {
+      const parsed = JSON.parse(raw) as OpenRouterErrorResponse;
+      message = parsed.error?.message || '';
+    } catch {
+      message = raw;
+    }
+
+    return {
+      statusLine: `${response.status} ${response.statusText}`,
+      message: (message || '').trim(),
+      raw,
+    };
+  }
+
   private createSystemPrompt(context: ContentContext): string {
     const isSeries = 'episodesBySeason' in (context as any);
     const isEpisode = !isSeries && 'showTitle' in (context as any);
@@ -349,6 +386,9 @@ Answer questions about this movie using only the verified database information a
         });
       }
 
+      const model = (await this.getPreferredModels())[0];
+      if (__DEV__) console.log('[AIService] Using model:', model);
+
       const response = await fetch(`${this.baseUrl}/chat/completions`, {
         method: 'POST',
         headers: {
@@ -358,7 +398,7 @@ Answer questions about this movie using only the verified database information a
           'X-Title': 'Nuvio - AI Chat',
         },
         body: JSON.stringify({
-          model: 'xiaomi/mimo-v2-flash:free',
+          model,
           messages,
           max_tokens: 1000,
           temperature: 0.7,
@@ -369,9 +409,17 @@ Answer questions about this movie using only the verified database information a
       });
 
       if (!response.ok) {
-        const errorText = await response.text();
-        if (__DEV__) console.error('[AIService] API Error:', response.status, errorText);
-        throw new Error(`API request failed: ${response.status} ${response.statusText}`);
+        const parsedError = await this.parseErrorResponse(response);
+
+        if (__DEV__) {
+          console.error('[AIService] API Error:', {
+            model,
+            status: parsedError.statusLine,
+            message: parsedError.message || parsedError.raw,
+          });
+        }
+
+        throw new Error(`API request failed: ${parsedError.statusLine} - ${parsedError.message || parsedError.raw || 'Request failed'}`);
       }
 
       const data: OpenRouterResponse = await response.json();