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GTM·Google Tag Manager·critical

Missing Google Ads Conversion Linker

Your container is missing the Conversion Linker. Every Google Ads conversion on the site is firing without the GCLID. Whenever the click lands on one page and the purchase happens two pageviews later (basically always), the click context is gone. Google still counts the conversion. It just can't tell you which ad caused it.

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By Christopher LandaverdeCreator of AdLint · ad-tech tracking specialistUpdated

Why It Matters

The chain looks like this. Someone clicks an ad. Google appends `?gclid=abc123...` to your landing URL. The Conversion Linker reads that `gclid` and writes it into a first-party cookie called `_gcl_aw`. The user browses, adds to cart, buys. Your Google Ads conversion tag fires on the order-confirmation page, pulls the GCLID back out of `_gcl_aw`, and sends the conversion with that ID attached. Google matches it back to the original click. Without the Conversion Linker, the cookie never gets written. The conversion tag still fires fine on the confirmation page, but the GCLID is gone, so the conversion lands at Google with nothing attached. Your dashboards keep populating off junk signal. Smart Bidding keeps optimizing off the same junk. Nothing tells you it's broken until reported ROAS stops matching the bank account. The longer the gap between click and purchase, the worse the bleed. A B2B funnel with a 30-day sales cycle loses almost all attribution. A multi-page checkout loses a chunk on every order. The conversion tag itself is healthy the whole time, so the dashboard looks normal. The damage shows up in reconciliation, months after you could have caught it.

Tag ManagerGTM-AB12CDE · Workspace: Default
BeforeTags
  • GA4 Configuration
    Type: GA4 Configuration
    Fires: All Pages
  • Google Ads. Purchase Conversion
    Fires without _gcl_aw set. GCLID lost.
    Type: Google Ads Conversion Tracking
    Fires: purchase_success
  • Google Ads. Lead Conversion
    Same. Lead reported without source attribution.
    Type: Google Ads Conversion Tracking
    Fires: form_submit
  • Google Ads. Remarketing
    Audience builds, but on degraded identifiers.
    Type: Google Ads Remarketing
    Fires: All Pages
Conversion tags are firing. The Conversion Linker is not. The GCLID never makes it into _gcl_aw, so every conversion tag below ships without click context.

Coloured rows show the configuration AdLint flags.

How To Fix It

  1. In GTM, hit New Tag, pick "Google Ads Conversion Linker."
  2. Trigger: All Pages.
  3. Multi-domain funnel (payment processor on a different domain, Shopify checkout, anything cross-host)? Open Linker Settings, turn on auto-link domains, paste every domain that appears in a real conversion path. Yes, the payment processor counts.
  4. Hit Preview. Load any page. Confirm the linker shows up in the Tags Fired panel.
  5. Publish. The finding clears on the next AdLint run.
Tag ManagerGTM-AB12CDE · Workspace: Default
AfterTags
  • Google Ads. Conversion Linker
    New tag. Writes _gcl_aw before any conversion fires.
    Type: Conversion Linker
    Fires: All Pages
  • GA4 Configuration
    Type: GA4 Configuration
    Fires: All Pages
  • Google Ads. Purchase Conversion
    Type: Google Ads Conversion Tracking
    Fires: purchase_success
  • Google Ads. Lead Conversion
    Type: Google Ads Conversion Tracking
    Fires: form_submit
Conversion Linker added on All Pages. It writes _gcl_aw on the landing page. Every downstream conversion tag now has the GCLID to send.

Green rows show the corrected state after the fix.

Example

Configuration
Tag type: Google Ads Conversion Linker
Trigger: All Pages
Auto-link domains: example.com, checkout.example-payments.com
For Your Client Report

This GTM container is missing the Google Ads Conversion Linker tag. Per Google's Tag Manager documentation, the Conversion Linker is required for Google Ads conversion tags to preserve ad click identifiers across pageviews. Without it, conversions on this site report without the GCLID that ties them back to the originating ad click. The effect is Smart Bidding optimizing on incomplete signal, and ROAS reports that diverge from actual revenue. Fix: add the Conversion Linker tag on the All Pages trigger and verify it fires before any downstream conversion tag. Source: support.google.com/tagmanager/answer/7549390.

Drop this paragraph into your client deliverable. Sources back to the canonical platform documentation linked below.

References

  1. [1]Google Tag Manager. Conversion Linker tag
  2. [2]Google Ads. About cross-domain measurement
  3. [3]Google Ads. GCLID and conversion attribution

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