# How to check Consent Mode v2 is working: a 10-minute test

A ten-minute checklist for whether Google gets the right consent signals: the defaults, Accept and Reject, two regions and the status in Google Ads.

_Shaun Brown · October 2, 2026 · https://tagsentry.ai/blog/check-consent-mode-v2-working_

> **The short answer:** Open your site in a private window with Google's Tag Assistant running. The first consent event should show all four signals already set, and denied in places that ask first. Accept should turn them to granted and Reject should leave them denied. Then run it again from a US connection and check the consent mode status in Google Ads.

This page is the checklist. If you want to know what Consent Mode is first, read [Google Consent Mode v2, explained without the jargon](/blog/google-consent-mode-v2-explained) and come back.

You need a private browser window, [Tag Assistant](https://tagassistant.google.com/) (Google's free debugging tool, the same thing as Tag Manager's Preview mode) and about ten minutes.

## The four signals you're checking

Consent Mode gives Google's tags a set of on/off switches. This test looks at four of them:

| Signal | In plain words |
|---|---|
| `ad_storage` | Can ad cookies be stored? |
| `analytics_storage` | Can analytics cookies be stored? |
| `ad_user_data` | Can data about this visitor be sent to Google for ads? |
| `ad_personalization` | Can it be used for remarketing and personalised ads? |

The "default" is what the switches say before the visitor answers your banner, and the "update" is what they say afterwards. You're checking both.

## Check 1: the defaults are set before any tag

Start Tag Assistant, enter your site's address, and let it open your site in a new tab. Don't touch the banner yet.

Back in Tag Assistant, pick the **earliest Consent event** in the left-hand list and open the **Consent** tab. The "On-page Default" column should list all four signals. If you're in a place where the law asks first, like the EU or the UK, each should say Denied.

The thing being tested is order. Google's guidance is that the default command must run before anything that sends measurement data, and that "if your consent code is called out of order, consent defaults won't work." In Tag Manager, that means the consent tag sits on the **Consent Initialization** trigger, which fires before every other trigger.

If an ad tag read or wrote a cookie before the default arrived, Tag Assistant flags it as an error. An empty Consent tab means Consent Mode isn't set up at all.

## Check 2: the update after Accept, and after Reject

Now click **Accept all** on your banner. In Tag Assistant, pick the **most recent Consent event**. The "On-page Update" column should show all four signals as Granted.

Then clear the site's cookies (or open a fresh private window), start again, and click **Reject all**. The update should keep all four Denied.

Then open the **Tags** tab and click through a few tags to see which fired and which were held. A Meta or Hotjar tag that fired after you rejected is a separate problem: those tags ignore Consent Mode, so Tag Manager has to hold them with its own consent settings. [Tag Manager's "consent settings not configured" warning](/blog/gtm-consent-settings-not-configured) covers that.

## Check 3: read gcs and gcd in the network panel

Tag Assistant shows what your page told Google, and the network panel shows what went out over the wire. Open your browser's developer tools (F12, or Cmd+Option+I on a Mac), go to the **Network** tab, reload, and type `gcs=` in the filter box.

Click any matching request and look at its query string for two values. Google describes `gcs` as carrying `ad_storage` and `analytics_storage`, and `gcd` as encoding the full consent detail for all the signals. Google doesn't publish a decoding table. People who work with these tags have worked one out.

**gcs, the short one.** It always starts `G1`. The third character is ads, the fourth is analytics. 1 means granted, 0 means denied.

| gcs value | ad_storage | analytics_storage | Where you'd expect it |
|---|---|---|---|
| `G100` | denied | denied | Ask-first region before Accept, or after Reject |
| `G110` | granted | denied | Visitor allowed ads but not analytics |
| `G101` | denied | granted | Visitor allowed analytics but not ads |
| `G111` | granted | granted | After Accept, or an opt-out region by default |

**gcd, the long one.** It looks like `13r3r3r3r5`. Reading Simo Ahava's breakdown, the letters after each `3` (or `1`) are, in order, `ad_storage`, `analytics_storage`, `ad_user_data` and `ad_personalization`. The letters you'll see most:

| Letter | Meaning |
|---|---|
| `l` | Signal never set |
| `p` | Denied by default, no update yet |
| `q` | Denied by default, still denied after update |
| `r` | Denied by default, granted after update |
| `t` | Granted by default, no update yet |
| `v` | Granted by default, still granted after update |
| `u` | Granted by default, denied after update |

An `l` in the third or fourth position means `ad_user_data` or `ad_personalization` was never set. These are Google's internal parameters and they can change, so if the two disagree, believe Tag Assistant.

## Check 4: test from two regions

A banner can pass every check above in London and still be wrong in Texas. Run the test twice, with a VPN or a colleague in another country.

1. **An ask-first place**, like Germany, France or the UK. Defaults should be denied, `gcs` should read `G100` until you click Accept.
2. **An opt-out US state without a privacy-signal law**, like Florida. If your setup follows US rules there, defaults are usually granted and `gcs` reads `G111` straight away.

If both regions behave identically, your banner is probably applying one set of rules to everyone. That's the usual reason [analytics drops after a banner goes up](/blog/why-analytics-dropped-after-cookie-banner).

Turn off any privacy extension for this test, and check your browser isn't sending the Global Privacy Control signal (a browser setting that tells sites "don't sell or share my data") unless that's what you mean to test.

## Check 5: the status in Google Ads

In Google Ads, go to **Goals**, then **Conversions**, then **Summary**, and look at the diagnostics. Google lists two healthy statuses, each with a green tick:

- **"Consent mode is implemented"**: it works, but you haven't reached the threshold for conversion modelling (Google's estimate of conversions it couldn't see). That threshold is 700 ad clicks over 7 days for a domain and country.
- **"Consent mode is implemented and modeling is active"**: modelling is running.

Google says the status can take 48 hours to appear, and up to two weeks in some cases. If you see neither after that (the "not detected" case), go back to Check 1. Ads reports what your tags sent; Tag Assistant shows you why.

## The usual failures, and what they look like

| What you see | Likely cause | Fix |
|---|---|---|
| Consent tab empty | Consent Mode isn't set up | Add defaults through your banner or a consent tag |
| "Default consent set too late" error | Banner script loads after Tag Manager, or its tag fires on All Pages | Put the defaults above the Tag Manager snippet, or on Consent Initialization |
| Defaults right, update never appears | Banner saves the choice but never sends the update | Ask your banner provider; the update must fire on every click |
| Same result from every region | Region settings missing or wrong | Use ISO codes like `DE` or `US-CA`; there's no single code for the EU, so list each country |
| `l` in the last two gcd positions | `ad_user_data` or `ad_personalization` missing | Add both to the default and the update; personalised ads need both granted |

On the region point: Google's setup guide says regions use ISO 3166-2 codes, and when a country and one of its states both have a default, the more specific one wins. A typo like `US-California` doesn't match anything, so that visitor falls back to whatever default has no region.

For which rules each region should get, see [how consent works](/docs/how-consent-works). Bear in mind that Tag Assistant checks one visit, the one you start. It won't tell you if something breaks next week. Our [comparison with GTM Preview](/compare/gtm-preview) is about that gap.

## Where TagSentry fits

TagSentry is one line of code above Google Tag Manager. It sets Google Consent Mode v2 before any tag runs: denied by default, and granted where visitors can opt out, unless they already have. That takes care of Checks 1 and 4.

The [free scan](https://app.tagsentry.ai/scan) checks whether your site has a banner and whether it stops trackers, if you want to see where you stand now.

## Sources

- [Google for Developers: Troubleshoot consent mode with Tag Assistant](https://developers.google.com/tag-platform/security/guides/consent-debugging)
- [Google for Developers: Set up consent mode on websites](https://developers.google.com/tag-platform/security/guides/consent)
- [Google for Developers: Consent mode overview (gcs and gcd parameters)](https://developers.google.com/tag-platform/security/concepts/consent-mode)
- [Google Ads Help: Verify consent mode implementation](https://support.google.com/google-ads/answer/14218557?hl=en)
- [Tag Manager Help: Consent mode reference](https://support.google.com/tagmanager/answer/13802165?hl=en)
- [Tag Manager Help: Consent settings and the Consent Initialization trigger](https://support.google.com/tagmanager/answer/10718549?hl=en)
- [Simo Ahava: Consent Mode V2 for Google tags (gcs and gcd decoding)](https://www.simoahava.com/analytics/consent-mode-v2-google-tags/)