How to tell if a pixel is actually working
A pixel can load and still not send events. Check the vendor library and the event it should send, plus the control that stops a false broken finding.
Last reviewed September 2026.
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. What a scan covers.
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.
Confirm it with a scan
Four page types, a real browser, no account. A scan will not fix the tag. It will tell you whether it is firing now.