Google Consent Mode v2: what it is and why ads work worse without it
If your website uses Google Analytics or you run Google Ads campaigns, you have probably heard of Consent Mode v2. It is not another banner or a new law. It is how a website tells Google's tools what the visitor has agreed to. Here is how it works and what happens when it is missing.
Consent Mode in plain words
Consent Mode is the mechanism a website uses to pass the visitor's cookie banner choice to Google Analytics, Google Ads and other Google tags. The tags adapt to it: with consent they work normally, without it they do not store advertising or analytics cookies.
Version 2 arrived because of the EU Digital Markets Act (DMA). Since March 2024, Google has required it from advertisers who want to measure and target visitors from the European Economic Area and the UK.
Four consent signals
The website sends Google four pieces of information. Two existed before, two were added in version 2:
- analytics_storage: whether analytics cookies, such as Google Analytics, may be stored.
- ad_storage: whether advertising cookies may be stored.
- ad_user_data: whether the visitor's data may be sent to Google for advertising (new in v2).
- ad_personalization: whether they may be shown personalised ads and remarketing (new in v2).
Basic and advanced mode
In basic mode, Google tags do not load at all until the visitor consents. If they reject, Google gets no data and estimates the missing conversions with a general model.
In advanced mode, the tags load straight away, but set to "denied". Without consent they store no cookies and only send anonymous signals with no identifiers, such as the fact that a visit or a conversion happened. From these, Google estimates the missing data more accurately than in basic mode.
It is worth agreeing on the mode with whoever is responsible for data protection in your business. Basic mode is more cautious, advanced mode gives fuller statistics.
What you lose without Consent Mode v2
If your website does not send consent signals and you have visitors from Europe:
- Google Ads cannot build remarketing lists from those visits, so you cannot show ads to people who have already been on your website.
- Conversion tracking is incomplete, and automatically optimised campaigns get less data and perform worse.
- Google Analytics shows less data and does not fill the gaps left by rejections.
- You risk breaching Google's EU user consent policy.
What it looks like technically
Before any tag loads, the website sets a default answer: everything denied. Only then do Google Tag Manager or the Google tag load. When the visitor makes a choice in the banner, the website sends a consent update, and the tags start working within what was agreed. On the next visit, the stored choice is restored straight away.
This website works that way: denied by default for every signal, Google Tag Manager only after that default, and an update after a choice in the banner, which you can reopen from the link in the footer.
You can also use a ready-made consent platform certified by Google, such as Cookiebot, CookieYes or Usercentrics. What matters is that someone checks the signals really reach Google, because installing a banner alone does not guarantee it.
How to check your website
A few quick tests:
- Open the website in a private window. Does the banner appear straight away, and does it have a "Reject" button?
- In Google Tag Manager, turn on preview mode and open the Consent tab: before any choice, all signals should be "denied".
- In Google Ads, check the conversion diagnostics to see whether Google receives consent signals.
- If you are not sure where to look, I check this as part of an audit, together with the website's speed and SEO.
Want to talk about your website?
See the service: Audit and optimisation, or write a few sentences about your business.
