When you see the yellow warning “Cart data needs attention” in your Google Ads conversion tracking diagnostics, it means your Purchase conversion event isn’t passing valid or complete product-level sales data — specifically, the items array required for Google Ads to understand which products were purchased. Let’s go step-by-step to fix this in Google Tag Manager (GTM), using a GA4 ecommerce dataLayer as your source. ⚠️ What the “Cart Data Needs Attention” Warning Means This diagnostic message typically appears in  Goals→ Conversions → Diagnostics → Cart data when: The Google Ads Purchase tag is missing the items array. The array exists but lacks one or more of these required keys: id (product/item ID) price quantity Your Merchant Center feed IDs don’t match the item_id values. Or the data format is invalid (not an array of valid objects). ✅ Step 1: Enable Product-Level Sales Data in the Purchase Tag In Google Tag Manager → Google Ads Conversion Tracking (Purchase): Scroll down and check “Provide product-level sales data”. Set the Data Source to Custom Fields. You’ll see a field called Items — this is where we’ll insert the correct array. If this field is left empty or malformed, your conversion will record...