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How to Detect External Sources Sending Facebook Events

If you're seeing unexpected Facebook events (like AddToCart, Purchase, or InitiateCheckout) even when you've configured Pixel Plus to avoid tracking them, this guide will help you detect if they're being triggered by external sources, such as:

  • Other Facebook-related modules
  • Manual JavaScript tracking code
  • Google Tag Manager (GTM)
  • Facebook's automatic event tracking features

✅ When to Use This Guide​

Use this diagnostic when:

  • You're seeing too many purchase events
  • The purchase event count is higher than your actual orders
  • Events are triggered even when disabled in the module
  • You want to verify that only Pixel Plus is sending Facebook events

🔍 Step 1: Disable All Events Except PageView​

Pixel Plus allows you to selectively enable or disable Facebook event tracking (except PageView, which is always sent).

How to do it:​

  1. Go to PrestaShop Back Office → Modules → Pixel Plus → Trackable Events
  2. Disable all event options like:
    • AddToCart
    • Purchase
    • InitiateCheckout
    • CompleteRegistration
    • and others
  3. Click Save

🧪 Step 2: Simulate Normal User Actions​

Now browse your site like a regular user:

  • Visit a product page
  • Add a product to cart
  • Start checkout
  • Complete an order (optional)
  • Submit a form, register, or apply a discount

🔬 Step 3: Monitor What Events Are Still Being Sent​

✅ Option A: Use Meta Pixel Helper​

Install from the Chrome Web Store

This tool shows:

  • All Pixel events triggered by the browser
  • Event parameters and origin

If you see any event other than PageView, it's not coming from Pixel Plus.

✅ Option B: Use Facebook Events Manager – Test Events Tool​

For a more complete view (including CAPI/server events), use the Test Events tool:

  1. Open Facebook Events Manager
  2. Select your Pixel and go to Test Events
  3. Copy the Test Code (e.g., TEST1234)
  4. Go to PrestaShop Back Office → Pixel Plus → CAPI section
  5. Paste the code into the Test Code field
  6. Enable Enable Test Code Events
  7. Click Add My IP to limit the test to your session (recommended)

⚠️ Important:
Disable the test code after your testing session.
Leaving it enabled without IP restriction can cause Facebook to flag your pixel or show errors.

🚨 Step 4: Interpret the Results​

  • If only PageView appears, your module is working as expected.
  • If other events appear, they're triggered by external sources.

🛠️ Step 5: Identify External Sources​

✅ 1. Other Modules​

Check for other Facebook-related PrestaShop modules or marketing tools that might trigger events independently.

✅ 2. Manual JavaScript​

Search your theme files or custom JS for:

fbq('track', 'Purchase');

Remove any manually placed tracking scripts.

✅ 3. Google Tag Manager (GTM)​

  • Open your GTM workspace
  • Look for Facebook-related tags (Purchase, AddToCart, etc.)
  • Disable any that may overlap with Pixel Plus

✅ 4. Facebook Event Setup Tool​

Facebook sometimes tracks events automatically.

To disable:

  1. Open Events Manager
  2. Go to your Pixel → Settings
  3. Disable:
    • Automatic Advanced Matching
    • Event Setup Tool

✅ Summary​

Using the Trackable Events configuration, Pixel Helper, and Test Events tool, you can:

  • Verify if unwanted events are triggered by Pixel Plus
  • Identify third-party tools or scripts that may interfere
  • Ensure clean, precise tracking across your store
How do I know if an event is being sent by Pixel Plus or by an external source?

Every event sent by Pixel Plus includes an event_trigger field set to Pixel Plus in the event payload. If this field is missing when you inspect the event in Meta Pixel Helper or the CAPI logs, the event was triggered by something else.

What is the fastest way to identify external event sources?

Disable all events in Pixel Plus except PageView, then browse your store and perform actions like adding to cart and completing checkout. Any events other than PageView that appear in Pixel Helper or Events Manager are coming from an external source.

Can Facebook's own automatic event tracking cause unexpected events?

Yes. Facebook offers an Event Setup Tool and Automatic Advanced Matching that can fire events independently. Go to Events Manager, select your Pixel, open Settings, and disable these features if you are using Pixel Plus for all tracking.

What should I look for in Google Tag Manager if events are duplicated?

Open your GTM workspace and review all tags for Facebook-related triggers, especially any tag that fires on the order confirmation page. Disable or remove any GTM tag that sends Purchase or other conversion events that Pixel Plus already tracks.

What should I search for in my theme files to find manual tracking code?

Search your theme files and custom JavaScript for the string fbq followed by track and a single quote. This pattern appears in all manually placed Facebook Pixel tracking calls. Remove or comment out any lines that fire events already handled by Pixel Plus.

Need help with duplicated Purchase events?
👉 Check out the full guide here