Fixing 3x Conversion Overcounting and Attribution for an Online Car Dealership

01// The broken state

Multiple installations of gtag.js and GTM caused duplicate event tracking in GA4. Conversion events were configured both directly in GA4 and through GTM, which inflated conversion counts threefold and corrupted attribution data. Login and sign-up events were also being miscounted, and hero banner video clicks were not tracked.

02// What we changed

1. aDebugged the GA4 and GTM setup and coordinated with the development team to remove the duplicate tracking script installations
2. bEliminated conversion events that had been configured directly in GA4 and implemented them exclusively through Google Tag Manager
3. cCorrected tracking for login and sign-up events
4. dAdded tracking for clicks on the main hero banner video
5. eResolved the attribution issues affecting source, medium, and campaign data

03// The outcome

With the duplicate scripts removed and conversion tracking rebuilt in Google Tag Manager, every conversion, login, signup, and video click now fires once and attributes to the right source. Ian, the Marketing Director, and his team could then confidently optimize their Google Ads (PPC) campaigns against numbers they trust.