The essentials
- Definition: Consent Mode v2 is the mechanism by which Google tags (GA4, Google Ads) adapt their behaviour to the user's consent choice, sending "granted" or "denied" signals for four purposes.
- The requirement: since March 2024, without Consent Mode v2, Google Ads no longer measures conversions or remarketing for European users.
- Two modes: basic (nothing is sent before consent) and advanced (anonymous cookieless pings, which feed the modelling).
- Setup: a compatible CMP, the consent template in GTM, a default state of "denied", an update on the user's choice.
Since March 2024, Google has required European advertisers to use Consent Mode v2 in order to keep measuring conversions and using remarketing. It doesn't replace the consent banner required by the GDPR and the French regulator; it connects that banner to the Google tags. This article explains the mechanism, the two modes, the setup with Google Tag Manager and a consent management platform, then the verification. GA4's legal framework is covered in GA4 and GDPR.
What Consent Mode v2 does exactly
| Content | Purpose | Effect if "denied" |
|---|---|---|
analytics_storage | Measurement cookies (GA4) | No GA4 cookie; in advanced mode, pings with no identifier |
ad_storage | Advertising cookies (Google Ads) | No click cookie, no cookie-based attribution |
ad_user_data (v2) | Sending user data to Google for advertising | No user data transmitted |
ad_personalization (v2) | Personalised advertising, remarketing | No addition to remarketing audiences |
The two parameters added by version 2 are the ones that determine Google Ads conversion measurement and remarketing in the European Economic Area. Without them, Google treats the user as having refused.
Basic mode or advanced mode
- Basic: the Google tags don't load until the user has consented. No data is sent before the choice. Google models conversions from a general model, with less precision. It is the most cautious mode from a regulatory standpoint.
- Advanced: the tags load on arrival with the "denied" state and send pings with no cookie and no identifier (no IP address retained, no cross-matching). Those pings let Google model the conversions and behaviour of users who refuse, recovering part of the lost measurement. The French regulator considers that such pings, if genuinely anonymous, may fall under the consent exemption, but recommends a case-by-case analysis.
For a small business that advertises, advanced mode is the one that preserves the most data; it requires a CMP that handles it properly and documentation in the privacy policy.
Setting it up with GTM and a CMP
- Choose a CMP compatible with Consent Mode v2 and certified by Google: Axeptio, Didomi, Cookiebot, CookieYes, Tarteaucitron (with the module), OneTrust. Most offer a GTM template.
- Declare the default state before any tag: the four parameters set to "denied" for European Economic Area visitors, with a
wait_for_updateof 500 ms to let the CMP respond. In GTM, this is done through the CMP's template (the template gallery) or a "Consent initialization" tag. - Update on the user's choice: the CMP sends
gtag('consent','update',{...})with the values matching the boxes ticked, and pushes an event into the dataLayer. - Configure the tags: in GTM, every Google tag reads consent automatically (built-in settings). For non-Google tags (Meta, LinkedIn), add the "additional consent settings" required, so that they fire only with
ad_storagegranted. - Turn on the consent overview in GTM (container settings) to see which tags have a consent configuration.
- Publish and check (next section).
For configuring the GA4 tags themselves, see GA4 with Google Tag Manager ; for Google Ads, Google Tag Manager and Google Ads.
Checking it works
| Control | How | Expected result |
|---|---|---|
| Default state | GTM Preview mode, Consent tab, before any click on the banner | The four parameters set to "denied" (in the EEA) |
| Update | Accept then refuse in the banner, watching the Consent tab | The values change with the boxes |
| Google tags | The Tags tab, consent column | Loaded with the right state; in basic mode, absent before consent |
| Pings (advanced mode) | Developer tools, Network tab, requests to google-analytics.com/g/collect | Content gcs=G100 (refused) or G111 (granted), gcd present |
| On the Google Ads side | Tools, Conversion diagnostics, Consent Mode section | Status "active", no warning |
| On the GA4 side | Admin, Data settings, Consent | Signals received |
| The Tag Assistant extension | A consent summary per tag | No tag without a consent setting |
The effects on your data
After deployment, expect: a fall in the number of users and sessions in GA4 (refusals are no longer counted as before, except through modelling), modelled conversions appearing in GA4 and Google Ads after 7 days if the volume thresholds are met (roughly 1,000 events a day with consent refused, for the model), and more complete attribution in Google Ads. Record the deployment date in your annotations so you can read the curves; the reading traps are in the GA4 traps to avoid.
The frequent mistakes
- A default state absent or sent after the tags: the tags load in granted mode before the choice.
- A CMP configured for v1:
ad_user_dataandad_personalizationare missing, and Google Ads loses its European conversions. - Non-Google tags with no consent condition: the Meta pixel fires whatever the choice.
- Treating Consent Mode as sufficient: the banner remains mandatory, with refusal as easy as acceptance.
- A banner that blocks everything in basic mode, with no modelling: measurement cut back unnecessarily.
How GreenRed helps
Rather than juggling several tools, GreenRed's GA4 Performance and traffic module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
Does Consent Mode v2 replace the cookie banner?
No. The banner (CMP) collects the consent required by the GDPR and the French regulator; Consent Mode passes that choice to the Google tags. Both are necessary: a banner without Consent Mode loses your Google Ads conversions, and Consent Mode without a compliant banner remains unlawful.
What happens without Consent Mode v2?
Since March 2024, Google Ads no longer measures conversions for users in the European Economic Area and no longer feeds remarketing audiences for accounts without v2 signals. Campaigns on automated bidding lose their optimisation data and their performance falls.
Is advanced mode compliant with the French regulator?
The CNIL accepts that strictly anonymous measurement with no cookie and no identifier may be exempt from consent, but it hasn't validated advanced mode as such. Many French companies use it with documentation in their privacy policy; the most cautious stay on basic mode. It is a decision to take with your legal adviser.
How do I know whether my conversions are modelled?
In Google Ads, the conversion report shows a "includes modelled conversions" note and the conversion diagnostics indicate the modelled share. In GA4, Admin then Data settings then Consent shows whether modelling is active, which requires daily volume thresholds.