GA4 Consent Mode v2:
What Changed and How to Check You're Compliant

If your site receives traffic from the European Economic Area, Consent Mode v2 is not optional. Google made it a requirement for all advertisers using Google Ads or Google Analytics on EEA traffic from March 2024. Properties that haven't implemented it are missing modelled conversion data, may be risking ad personalisation features, and are operating in a grey area on data compliance.

This guide explains what Consent Mode v2 actually does, what changed from v1, and exactly how to verify your implementation is working.

What Consent Mode actually does

Consent Mode doesn't replace your cookie consent banner — it works alongside it. When a user interacts with your CMP (consent management platform), their consent choices are passed to Google's tags as consent signals. Google then adjusts what data it collects and how it processes it based on those signals.

The key thing Consent Mode enables that nothing else can: conversion modelling. When a user declines analytics cookies, GA4 can't directly observe their behaviour. But with Consent Mode active, Google uses machine learning to model what those users likely did — filling in the gaps caused by cookie refusal without recording individual data. Without Consent Mode, those users are simply invisible in your reports.

What changed from v1 to v2

Consent Mode v1 had two consent signals: analytics_storage and ad_storage. Consent Mode v2 adds two more, and those two new ones are the reason the update matters:

Properties still on Consent Mode v1 — or with no Consent Mode at all — are missing ad_user_data and ad_personalization. Google cannot properly handle EEA user data for advertising without them.

What happens without Consent Mode v2

For most EEA-facing sites, cookie consent decline rates run 20–40%. Without modelling, that's 20–40% of your conversion data that simply doesn't exist in your reports. For Google Ads campaigns, it means Smart Bidding is working with substantially incomplete data.

How to verify your implementation

• 1
  Check GA4 Admin → Data Streams → Consent Overview Open your web data stream and look for the Consent Overview section. This shows what percentage of events in the last 7 days included each consent signal. If you see 0% or no data for ad_user_data or ad_personalization, those signals aren't being sent.
• 2
  Use GTM Preview to inspect consent state Open GTM Preview on your site. Navigate to the Variables tab and look for the Consent State variable (if configured). When you decline cookies in your consent banner, you should see the relevant signals switch to "denied". If nothing changes, your CMP isn't communicating with Consent Mode.
• 3
  Check the Network tab for consent signals Open browser dev tools → Network tab → filter for "collect" or "gtag". When a GA4 hit fires, inspect the request payload. You should see gcs parameter (Google Consent State) with values like G111 (all granted) or G100 (analytics denied). If gcs is missing, Consent Mode isn't active.
• 4
  Test both consent states Accept all cookies and verify GA4 collects normally. Then clear cookies, reload, and decline all cookies. You should still see GA4 network requests (cookieless pings) but with gcs reflecting denied consent. If GA4 fires no requests at all when cookies are declined, Consent Mode isn't configured as "Basic" mode minimum.

How to implement it

If you're using a CMP (OneTrust, Cookiebot, CookieYes, Usercentrics, etc.), most of them now have native Consent Mode v2 support. You typically need to:

1. Update your CMP to the latest version
2. Enable Consent Mode v2 in your CMP's settings
3. Ensure your CMP's GTM template or script is configured to pass all four signals
4. Set default consent states (usually denied for all four) before the CMP loads

The default consent state matters. Consent Mode requires you to set a default state — what Google's tags assume before the user has made a choice. For EEA traffic this should be denied by default, updating to granted when the user consents. Setting defaults to granted and only denying on opt-out is the wrong approach for GDPR purposes.

Check your Consent Mode automatically

Our audit checks whether Consent Mode v2 signals are present in your GA4 property, verifies that all four required signals are being sent, and flags properties that are still on v1 or have no Consent Mode implementation at all. It's one of 47 checks we run in under 60 seconds.

Run your GA4 audit — $179 →

Travis Gunn

Founder of GA4 Health Check. Working with Google Analytics since 2013, with over 250 clients audited across almost every industry vertical. 100% Job Success on Upwork for over a decade.