Consent Mode v2 tells Google whether each visitor accepted cookies. If it's missing or set up wrong, GA4 and Google Ads lose the visitors who decline, and Google can't model the conversions you miss. Here is how to check it in a few minutes.
What Consent Mode v2 sends
Consent Mode passes four signals to Google with every request: ad_storage and analytics_storage (the original two), plus ad_user_data and ad_personalization, added in version 2. Since March 2024 Google has required the two newer signals for visitors from the European Economic Area to keep remarketing and conversion measurement working.
A correct setup does three things: it sets a default state before any Google tag runs, usually denied for visitors who must be asked; it updates the state when the visitor clicks your banner; and it keeps every other tag (Meta, LinkedIn, TikTok) waiting for the same choice.
Check 1: the one-minute test
Our free Tracking Check loads your page in a real browser without clicking anything, then reads the consent state that Google's own requests carry. It tells you whether Consent Mode v2 is there, what the default state is, and which tags sent data before a choice.
Check 2: in your browser
- Open your site in a private window, so no earlier choice is stored, and don't click the banner.
- Open Chrome's developer tools (right-click, Inspect), go to Network and type
collectin the filter. - Reload the page and click a request to
google-analytics.com/g/collect. Look at two parameters:- gcs:
G100means ad and analytics storage are both denied;G111means both are granted. - gcd: a short code with one letter per signal. If every letter is
l(as in13l3l3l3l1), Consent Mode isn't set up at all.
- gcs:
- Click "Accept" on your banner and check the next request: the state should change to granted.
If you see no collect request before the click, your tags wait for consent (basic mode). That respects the choice, but without Consent Mode Google gets no signal at all from people who decline.
Check 3: Google Tag Assistant
Google's Tag Assistant (tagassistant.google.com) connects to your site and shows, for each event, the default and updated state of every consent signal. It's the clearest view if you use Google Tag Manager.
The five most common mistakes
- Tags fire before the default is set. The consent default has to load before GA4 and Google Ads, for example with a Consent Initialization trigger in Tag Manager.
- Version 1 only. ad_storage and analytics_storage are set, but ad_user_data and ad_personalization are missing.
- The banner doesn't send signals. Many banners support Consent Mode, but the switch is off.
- Other pixels ignore the banner. Meta, LinkedIn or TikTok fire on page load while Google waits.
- Everything granted by default. A default of granted for every visitor means no one is really asked.
How Hong Kong companies do
In our November 2026 study of Hong Kong companies listed on HKEX, 9% of the websites with Google tags sent Consent Mode v2 signals, and 57% of those with a consent banner still sent data before the visitor chose.
Frequently asked
What is the difference between basic and advanced Consent Mode?
In basic mode, Google tags don't load until a visitor accepts, so nothing is measured for people who decline. In advanced mode, tags load with consent denied and send cookieless pings, which Google uses to model the conversions you can't see.
Do Hong Kong websites need Consent Mode v2?
Hong Kong has no cookie-banner rule like Europe's, but Google requires Consent Mode v2 signals for visitors from the European Economic Area. If you advertise to Europe, or want Google to model conversions from people who decline cookies, you need it.
Can a cookie banner work without Consent Mode?
Yes, but then Google gets no signal from visitors who decline, so they simply disappear from GA4 and Google Ads. Most consent banners (Cookiebot, OneTrust, Usercentrics, CookieYes and others) can send Consent Mode signals for you once it is switched on.