Google Ads Auto-Tagging Conflicts with Manual UTMs in GA4

How Auto-Tagging and UTMs Interact

Google Ads auto tagging appends a GCLID (Google Click Identifier) parameter to the destination URL when a user clicks an ad.

GA4 reads this GCLID and uses it to import click level data from Google Ads, campaign name, ad group, keyword, match type, and other dimensions that are not available through UTM parameters alone.

Manual UTM parameters are also sometimes added to Google Ads destination URLs by advertisers who want to control the source/medium values that appear in GA4 reports.

When both are present, GA4 has a decision to make: which attribution source should take precedence?

GA4's default behaviour is to prefer the GCLID when both are present, it ignores the manual UTMs and uses the auto tag data instead.

This is usually the right behaviour, but it creates problems when the manual UTMs were intentionally added to categorise or subcategorise the traffic in a specific way, or when the GCLID lookup fails because the Google Ads link to GA4 has not been properly configured.

When Auto-Tagging Goes Wrong

Auto-tagging attribution failures in GA4 almost always trace back to one of three causes.

First, the Google Ads account is not linked to the GA4 property, without the link, GA4 receives the GCLID but cannot resolve it against the Ads data, causing the traffic to appear as google/cpc but without campaign level detail.

Second, the landing page strips the GCLID parameter before GA4 can read it.

This happens with some redirect configurations, URL canonicalisation setups, or website platforms that clean "unknown" query parameters from landing page URLs.

When the GCLID is stripped, GA4 cannot attribute the session to the Google Ads click, and the session typically falls back to organic or direct.

Third, the destination URL includes ValueTrack template tokens, such as lpurl, that are not resolving correctly. That leaves the final URL malformed and causes the GCLID to be appended to an invalid destination.

Each of these failures has a specific diagnostic approach, and the symptom is the same: Google Ads click volume in the Ads platform does not match Google Ads session volume in GA4.

Best Practice: When to Use Auto-Tagging vs Manual UTMs

For Google Ads campaigns linked to GA4, auto tagging should be the primary attribution mechanism, it provides richer data than UTMs alone and is required for Smart Bidding to function correctly with GA4 imported conversions.

Manual UTMs on Google Ads destination URLs should only be used when auto tagging is known to be broken (for example, a website that strips GCLIDs and cannot be modified) or when a specific segmentation requirement cannot be met with auto tag data.

If manual UTMs are added alongside auto tagging, test carefully to confirm they are not interfering with GCLID reading, use GA4 DebugView to inspect the session source after clicking a Google Ads ad and verify the session is attributed to google/cpc with campaign detail rather than to the UTM source values.

The Google Ads Diagnostics tool in the GA4 Admin linked accounts section can also identify specific auto tagging configuration problems at the account level.