Google Consent Mode v2 Explained: Keep GA4 Reports & Ads Accurate with a Certified CMP
Summary
In 2025, websites using GA4 or Google Ads in the EEA and UK are expected to implement Consent Mode v2 using a Google-certified Consent Management Platform (CMP). Without this setup, data collection is limited, remarketing becomes less effective, and conversions are underreported.
Websites operating in the European Economic Area (EEA) and the UK are now expected to implement Consent Mode v2 when using Google Analytics 4 (GA4) or Google Ads. This update requires passing verifiable user consent signals to Google, which directly influences data reporting, conversion tracking, and ad campaign effectiveness. Without these signals, GA4 and Ads reports become less complete, remarketing audiences shrink, and campaign performance may decline. (Google Ads Help).
Consent Mode v2 is designed to support both privacy compliance efforts and accurate measurement strategies. To operate within Google's updated requirements, businesses need to adopt a certified Consent Management Platform (CMP). Clym is a Google-certified CMP that helps transmit the appropriate consent signals, providing businesses with a streamlined path to maintain reporting continuity while respecting user preferences.
What is a certified CMP and why it matters
A certified Consent Management Platform is officially recognized by Google for its ability to send structured, accurate consent signals.
Without certification:
- Signals may be rejected
- Behavioral modeling fails
- Reporting degrades
Because Clym is certified by Google, the signals it passes align with the technical standards expected for Consent Mode v2.
What’s new in consent mode V2 for GA4 and Google Ads
Consent Mode v2 asks websites to share four simple answers with Google about what each visitor agreed to. Here's a simplified explanation of the Google Analytics consent guide:
Consent area | What it means |
|---|---|
Measurement (analytics) | Can visits be measured? |
Ad storage | Can cookies be used for ads? |
Ad user data | Can personal data be used in ads? |
Ad personalization | Can ads be tailored to individuals? |
If these signals are not sent, Google assumes the answer is “no,” resulting in incomplete tracking and weaker ad targeting.
What happens if you do not enable Consent Mode v2
Without Consent Mode v2:
GA4 reports shrink: fewer site visits and conversions are recorded
Remarketing audiences decline: less data available for ad targeting
Campaign optimization suffers: machine learning tools lose signal inputs
All of these issues directly impact ROI from advertising and analytics investments.
How Google fills data gaps through modeling
When visitors say “no,” GA4 doesn’t store personal data. Instead, it estimates results using behavioral modeling, comparing visitors who gave consent to those who didn’t (GA4 behavioral modeling).
But modeling only works if your website has set up Consent Mode v2 correctly. If tags are blocked or signals are missing, even modeling cannot run (GA4 tag guidance).
How to set up Consent Mode v2 correctly
To meet Google’s requirements, businesses need a certified CMP. The steps are:
Show a consent banner: visitors are asked to opt-in or opt-out of analytics and advertising.
Translate consent into signals: the CMP turns user choices into signals for Google.
Send signals to GA4 and Ads: your analytics and ad tools receive consent status.
Verify your setup: use Google’s Tag Assistant to ensure signals are being received correctly.
Using a certified CMP is essential. Non-certified platforms may send invalid signals that Google will reject.
Risks of skipping Consent Mode v2 implementation
Risk | Impact on business |
|---|---|
Incomplete reports | Poor decisions based on missing data |
Shrinking audiences | Less effective remarketing campaigns |
Underreported conversions | Ads seem less profitable than they are |
Compliance issues | Google rejects invalid consent signals |
How Clym simplifies Consent Mode v2 implementation
Clym is a Google-certified CMP that makes implementation straightforward:
- Certified by Google: signals are recognized as valid.
- Automatic consent passing: handles the four consent categories (
ad_storage,analytics_storage,ad_user_data,ad_personalization) automatically. - Built-in consent banner: facilitates compliance with GDPR rules.
- Supports IAB TCF: covers both Google’s requirements and industry standards.
- Keeps reports reliable: GA4 can model conversions, and Ads campaigns optimize more effectively.
Explore Clym’s Consent Management solution
Conclusion
Consent Mode v2 is about balance: respecting visitor privacy while preserving accurate reporting. For businesses in the EEA and UK, it’s not optional. Without a certified CMP, measurement, and advertising performance declines.
With Clym, a Google-certified CMP, businesses can implement Consent Mode v2 quickly, pass signals automatically, and keep GA4 and Ads reporting consistent while honoring visitor choices.
FAQs
It’s Google’s way of asking websites to send clear yes/no answers about visitor consent for measurement and ads.
Yes. Google requires a certified CMP in the EEA and UK to make consent valid.
Google assumes visitors said “no.” Reports shrink, conversions drop, and ad audiences get smaller.
GA4 uses modeling , comparing consented and non-consented traffic , to estimate results, but only if signals are sent correctly.
Clym, as a certified CMP, automatically passes the required signals. It connects banner choices directly to GA4 and Ads, so businesses don’t need technical expertise.
Yes. Clym also supports IAB TCF, helping businesses cover both Google’s rules and broader frameworks.
Without Consent Mode v2, remarketing audiences shrink and conversions are undercounted, reducing campaign effectiveness.
Alex is a Content Developer at Clym, where he researches and writes about everything related to data privacy and web accessibility compliance for businesses, helping them stay informed on their compliance needs and spreading awareness about making the web safer and more inclusive. When he’s not writing about compliance, Alex has his nose in a book or is hiking in the great outdoors.
Find out more about Alex