Consent Mode v2: the four parameters and what you lose without it

What is Consent Mode v2?

Consent Mode v2 is a Google mechanism for telling its tags the state of cookie consent. The tags read that signal and adjust: with consent they behave as always; without it, they hold back.

Two things get confused daily. The cookie banner asks the visitor, and consent mode passes their answer to Google. Having a banner without consent mode means you ask and tell nobody.

The confusion started with how it was sold. Many banner vendors advertised «Consent Mode included» when what they included was the ability to connect it, not the connection itself. That gap explains most of the half-finished setups we find.

What does each parameter control?

There are four, with exact technical names worth recognising when they turn up in a configuration.

• ad_storage: the use of Google advertising cookies and Analytics identifiers.
• analytics_storage: the storage of analytics data.
• ad_user_data: sending user data related to advertising to Google.
• ad_personalization: personalised advertising.

The first two existed before. The last two were added in November 2023, and they are precisely what turns v1 into v2. When somebody says they «have Consent Mode» and those two are missing, they have the old version.

Each parameter takes one of two values, granted or denied, and they travel together. A common European setup grants analytics_storage and denies the three advertising ones when the user accepts only technical and measurement cookies. That is legitimate and changes a great deal about what Google can do with the data afterwards.

Default values also need setting before any tag loads. If tags run before the consent state is known, the sequence stops making sense and the signal arrives late.

Basic and advanced: the decision that matters

This is the real choice at implementation, and it changes both the measurement and the legal profile.

In basic mode, Google tags do not load until the user interacts with the banner. Nothing leaves for Google before that decision. It is the most conservative setup and the one that collects least.

With advanced mode, tags load with default values and send cookieless signals before the decision. Google receives anonymous pings that identify nobody but let it estimate what it cannot measure.

The practical difference sits in conversion modelling. With advanced mode Google builds a model specific to your account. With basic it applies a general, less refined one. On low-volume accounts that gap shows.

The choice between them goes beyond the technical. Advanced mode sends signals before the user decides, and although they are anonymous, some legal advisors prefer not to. It is a conversation worth having with whoever handles data protection, rather than settling by default from the technical side.

Our practical recommendation: for businesses with high volume and clear legal guidance, advanced. For smaller companies or where there are doubts, a well-built basic beats a badly built advanced.

What do you lose without it?

First and most obvious. Conversions from anybody rejecting cookies stop being counted, and across Europe that is a substantial share of traffic. The Google Ads account sees fewer conversions than exist, and automated bidding optimises against a trimmed reality.

The second is less obvious and more expensive. Without that signal, remarketing audiences come up short and imported conversions stop matching real sales. That gap surfaces later when the platform is compared against the CRM, the problem we cover in offline conversions.

And there is a knock-on effect: reports end up incomplete if consent is not updated properly on page transitions, as Google’s own documentation warns.

What is conversion modelling?

When somebody rejects cookies, Google cannot attribute their purchase to any ad. Rather than counting it as zero, it estimates how many such conversions are happening based on the behaviour of users who did accept.

That explains a question we get often: why Google Ads reports more conversions than Analytics. Part of those conversions are modelled rather than measured one by one. It is neither an error nor artificial inflation, but worth knowing before comparing two tools that count differently.

Modelling needs volume to work. On small accounts Google may lack the data and fall back on what it measures directly, which reduces the effect of advanced mode. The other way to recover signal is sending first-party data, which Google now gathers in Data Manager.

How to tell whether yours is set up properly

Three checks anybody can run in ten minutes without touching anything.

1. Open the site in a fresh window and reject cookies. If Google tags still write cookies, it is wrongly implemented.
2. In Google Tag Manager preview mode, check that all four parameters appear and change when accepting or rejecting.
3. In Google Ads, look for the consent notice in the account diagnostics.

The failure we see most is not the absence of consent mode but a bad connection. The banner stores the choice and nobody passes it to the tags. From outside it looks right and inside it does nothing.

The second most common failure is load order. Tags fire before the banner has set the default values, so for a few milliseconds Google receives a state that does not match reality.

The four mistakes we see most

After reviewing many setups, the failures repeat with surprising regularity.

1. The banner passes nothing on. It stores the choice in the browser and stops there. The most common and the most invisible.
2. The two new parameters are missing. The setup sends ad_storage and analytics_storage but not ad_user_data or ad_personalization. That is the old version running under a new name.
3. Defaults arrive late. Tags fire before the banner sets the initial state.
4. Nobody checks afterwards. It gets implemented, signed off, and six months later a cookie-tool update has disconnected it without any alert.

The fourth deserves attention. This is not a one-off installation: it is worth rechecking whenever the banner, the tag manager or the site template changes.

Who actually needs it

Any site using Google Ads or Analytics with traffic from the European Economic Area, Switzerland or the United Kingdom, which is where Google applies different regional behaviour.

If your traffic comes entirely from outside Europe, consent mode adds little. If you sell in Europe, it is basic infrastructure rather than an extra, like properly built measurement.

Where to start

Run the first check on the list above: open your site, reject cookies and see whether Google cookies get written anyway. That two-minute test separates the sites that have this solved from the ones that think they do.

If it fails, the fix is connecting the banner you already have to the tags, not replacing it. That is tagging and consent management work rather than design work.

Frequently asked questions