Consent Mode v2 is Google's framework for handling user consent signals across GA4 and Google Ads. It was made mandatory for EEA traffic in March 2024 as part of Google's compliance with the Digital Markets Act. Despite this, a significant proportion of properties we audit still have no Consent Mode v2 implementation in place — meaning they are running out of compliance and operating with degraded conversion data for any user who declines cookie consent.

Consent Mode v2 is a set of four consent signals that your Consent Management Platform (CMP) passes to Google's tags. These signals tell Google what a user has consented to — and what they haven't — so that Google can handle their data accordingly.

The four consent parameters are:

The first two (ad_storage and analytics_storage) existed in Consent Mode v1. The addition of ad_user_data and ad_personalization is what constitutes v2 and what Google requires for EEA compliance.

What happens to your data without Consent Mode v2

When a user declines cookie consent and Consent Mode v2 is not implemented, Google's tags cannot fire for that user at all. The conversion simply does not get recorded — it falls into a gap in your data. You have no visibility into what that user did, what channel they came from, or whether they converted.

When Consent Mode v2 is correctly implemented, Google uses a privacy-preserving modelling technique called conversion modelling to estimate the behaviour of users who declined consent, based on patterns from users who did consent. This modelled data is then included in your reports and fed back into Smart Bidding algorithms.

The performance impact: Smart Bidding algorithms in Google Ads optimise based on the conversion signals they receive. If 30–40% of your EEA conversions are invisible because Consent Mode is missing, Smart Bidding is optimising against a fraction of your actual conversion data. This directly degrades campaign performance for your EU traffic.

Basic mode vs Advanced Consent Mode

There are two implementation modes, and they behave very differently:

Basic Consent Mode

Google's tags only load after the user makes a consent choice. If the user declines, no tags fire at all — and no modelling occurs. This is technically compliant but provides no conversion modelling benefit.

Advanced Consent Mode

Google's tags load immediately on page load, but in a cookieless, privacy-safe state. They send consent signals to Google before a user makes a consent choice. When a user declines, cookieless pings continue to be sent — giving Google enough signal to model conversions. This is the implementation that enables conversion modelling and is the approach Google recommends.

Use Advanced Consent Mode. Basic Consent Mode satisfies the compliance requirement but delivers none of the modelling benefits. Advanced Consent Mode gives you compliance and better data. The implementation effort is similar — always target Advanced.

How to implement Consent Mode v2

Step 1: Choose a Google-certified CMP

The easiest implementation path is through a Consent Management Platform that has native Consent Mode v2 integration with Google. Google maintains a list of certified CMPs. Cookiebot (by Usercentrics), OneTrust, and Didomi are the most commonly used. These platforms handle the signal passing automatically once configured.

Step 2: Configure default consent states

Your CMP should set default consent states before any tags fire. For EEA users, best practice is to default all consent parameters to denied until explicit consent is given. This is the conservative approach and the one Google recommends for regulatory compliance.

Step 3: Implement via Google Tag Manager

In GTM, enable the Consent Overview feature under Admin → Container Settings. This gives you visibility into which tags have consent checks configured. Your CMP should provide a GTM template that handles the consent signal passing — install this template, configure it with your CMP settings, and publish.

Step 4: Verify signals in GA4 DebugView

After implementation, use GA4 DebugView (Admin → DebugView) to verify that consent signals are being received correctly. You should see consent update events firing with the correct parameter values. Check both the consented and declined user journeys.

Step 5: Check the Consent Mode report in GA4

GA4 has a built-in consent report under Admin → Data Display → Consent Settings. This shows you what percentage of your traffic is sending consent signals and what states they are in. If the report shows no consent signals detected, your implementation is not working.

How to verify your Consent Mode v2 status

GA4 Health Check's automated audit checks for Consent Mode v2 signals in your property data and flags the issue if no signals are detected. It is one of the checks in our Privacy & Compliance module — one of 47 checks run across your property in under 60 seconds.

If your property has EEA traffic and no Consent Mode v2 implementation, this will appear as a high-priority finding in your audit report, with remediation guidance and links to implementation resources.

Run a GA4 audit to check your Consent Mode v2 status →

If you have EU traffic and no Consent Mode v2, you have two problems: a compliance risk and a data gap. Both are fixable. The implementation takes a few hours with a certified CMP. The cost of leaving it in place is ongoing. Run an automated audit →
Travis Gunn
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.