How to tell if a pixel is actually working

Installed is not the same as working

A snippet in the theme, a green light in a pixel helper, and a 200 on the vendor’s JavaScript all say the same limited thing: the library was asked for. They do not say an event left.

Two observations, every time

For GA4 the pair is gtag/js (or the GTM container that injects it) and/g/collect with the event name. For Meta it is the pixel library andfacebook.com/tr (or the current collect host) carrying that event. Other vendors have their own pair; the shape does not change.

Library present with no collection request is the finding. It is the one tools that only scrape the HTML cannot see. How the scanner decides.

Do it on four page types

A pixel that fires on home and stays silent on product will keep a dashboard from looking empty. That is how the failure hides.A theme update is the usual way one type drops out.

The control

If nothing on the page fired — not even the store’s own first-party request — you cannot call the vendor broken. The page may have been a challenge, a consent wall, or a failed load. Tagnovo reports that as unobservable and will not emit a broken finding there.

A Google Analytics alert cannot do this test. It only sees events that arrived.Why GA4 alerts miss a silent tag.