Last updated September 3, 2026 · By Vishal Swami, Founder & Lead AI Reviewer, AISagely
Firefox's AI switch is off. Telemetry isn't. That's what an independent network test of Firefox 155 found the same week the browser shipped. It's the opposite of what the setting's name implies. Mozilla's "Block AI enhancements" toggle has been live since Firefox 148 in February 2026. It does shut off every generative feature the company has built: the sidebar chatbot, AI tab groups, link-preview summaries, PDF alt text, translations, and the newer Smart Window. But a fresh packet capture against Firefox 155 found none of that touches a single telemetry ping, ad-network request, or tracking identifier. Two fresh profiles — one with AI blocked, one left on defaults — sent Mozilla's servers identical traffic, down to the request count.
Short answer: Firefox's "Block AI enhancements" toggle (Settings, then AI Controls, on Firefox 148 or later) turns off generative features like the sidebar chatbot, AI tab groups, and Smart Window. It does not reduce telemetry. A September 2026 network test of Firefox 155 found identical telemetry pings, ad-network traffic, and tracking identifiers whether the switch was on or off.
What "Block AI enhancements" actually turns off
Mozilla calls it "AI Controls," not a kill switch. CEO Anthony Enzor-DeMeo made that distinction explicitly in an August 25, 2026 essay titled "Trust is earned. Consent is asked. AI skipped both." As of Firefox 155, the toggle sets eleven browser preferences at once, up from nine when it launched in Firefox 148. Turning it on blocks several things at once: the sidebar chatbot, AI-generated tab groups, link-preview "key points" summaries, automatic PDF alt text, built-in translations, Smart Window, and any extension that hooks into Firefox's supplied AI models. It also hides the pop-ups and in-browser nags promoting current or upcoming AI tools. You'll find it under Firefox, then Settings, then AI Controls in the left sidebar, per Mozilla’s own support documentation. Your choice persists across future updates.
That's a real, functioning setting. It's just narrower than its nickname suggests. It governs generative AI features specifically. It was never built to touch the browser's separate data-collection system, and Mozilla's own materials never claimed it would. The confusion comes from users assuming "AI off" means "less of my browser talking to Mozilla." That's a reasonable assumption for a name like "kill switch" to invite, even though Mozilla itself prefers "AI Controls" for exactly that reason.
What I found when I tested the claim myself
When I tested this claim against Mozilla's own documentation and the underlying network data researchers have now captured twice, both sides of the story check out. In my testing of the sourcing, the gap isn't a rumor or a single blogger's guess — it's a repeatable measurement. A developer first ran Wireshark against Firefox 148 in March 2026 and counted 25 TLS hosts and 76 DNS queries on a fresh profile's first launch. They retested against Firefox 155 on September 1, 2026, the day it shipped, and found first-launch contacts had dropped to 14 hosts and 70 queries — real, verifiable progress on the number of parties Firefox talks to when you first open it.
The part that didn't move is what happens after that. During a 120-second idle window with no user activity, both a default profile and an AI-blocked profile contacted nine TLS hosts and sent 14 telemetry POST requests to incoming.telemetry.mozilla.org, including eight messaging-system pings apiece — identical counts, not just similar ones. Both idle runs also called the ad-preflight endpoint at ads.mozilla.org and established six TLS handshakes with ads-img.mozilla.org. Both prefetched a DNS lookup for temuaffiliateprogram.pxf.io — a Temu affiliate-marketing tracker — within about three seconds of a fresh launch. And the persistent identifiers that tie your browser to Mozilla's telemetry system, including the Glean client ID and legacy telemetry client ID, were unchanged whether AI was blocked or not. As the retest put it: "The switch rotates nothing and deletes nothing."
There's a sharper detail underneath that: Firefox requested an AI-related Remote Settings collection named ai-window-prompts 23 to 24 seconds into a brand-new profile's very first launch — while the user was still inside Firefox's mandatory first-run notice, before the AI Controls setting was even reachable. Consent, in other words, wasn't asked before that first AI-adjacent network call went out.
How to actually turn off Firefox's AI features
1. Update to Firefox 148 or later
AI Controls doesn't exist on older versions. Firefox 155, current as of September 1, 2026, has it; check Firefox menu, then About Firefox to confirm your version and trigger an update if needed.
2. Open Settings, then AI Controls
The section lives in the left sidebar of Firefox's Settings page, per Mozilla's support documentation — not buried inside Privacy & Security, where most people would look first.
3. Toggle "Block AI enhancements," or pick features individually
The master toggle blocks everything at once. Below it, Mozilla lists each generative feature separately if you'd rather keep one (translations, say) and drop the rest.
4. Don't expect it to touch telemetry
This step is the one people skip: AI Controls and Firefox's data-collection settings are two unrelated systems, and switching one does nothing to the other.
5. Turn off telemetry separately, in Privacy & Security
Go to about:preferences#privacy and uncheck everything under "Firefox Data Collection and Use," then restart the browser. That's the setting that actually reduces what Firefox reports back to Mozilla — AI Controls was never it.
What "Block AI enhancements" turns off vs. what keeps running
| Category | Turned off by the AI toggle | Keeps running either way |
|---|---|---|
| Generative features | Sidebar chatbot, AI tab groups, link-preview summaries, Smart Window, PDF alt text, translations, AI-hooked extensions | — |
| Promotional pop-ups | In-browser nags for AI features | — |
| Idle telemetry (120s) | — | 9 TLS hosts, 14 POST requests to incoming.telemetry.mozilla.org, identical on both profiles |
| Ad-network calls | — | ads.mozilla.org preflight, 6 TLS handshakes with ads-img.mozilla.org |
| Affiliate tracker | — | DNS prefetch to temuaffiliateprogram.pxf.io within ~3 seconds of launch |
| Tracking identifiers | — | Glean client ID, legacy client ID, profile-group ID — unchanged either way |
| First-run AI request | — | ai-window-prompts collection requested 23–24 seconds in, before the setting is reachable |
Numbers from the Firefox 155 retest published September 2, 2026, comparing a default profile against one with "Block AI enhancements" already on.
Example prompts you can copy
Paste these into any AI chat tool if you want help auditing your own Firefox profile instead of taking a headline's word for it:
“ I just turned on Firefox's "Block AI enhancements" setting. Walk me through opening about:preferences#privacy and identify every checkbox I'd need to uncheck to also reduce telemetry, and explain in plain English what each one actually reports to Mozilla. “
“ Explain the difference between Firefox's Glean telemetry client ID and its legacy telemetry client ID, and whether either one is supposed to reset when a user changes an AI or privacy setting. “
“ I want to confirm my Firefox profile isn't contacting an ad-preflight domain or an affiliate-marketing domain like a *.pxf.io address on startup. What's the simplest built-in way to check outgoing connections without installing packet-capture software? “
These work because they point the assistant at a specific, checkable setting or log instead of asking it to summarize "Firefox privacy" in general, which tends to produce a vague answer that doesn't match your actual profile.
Common mistakes to avoid
In my testing of this claim, the mistake I nearly made myself was assuming "Block AI enhancements" was a general privacy switch, since that's what the "kill switch" framing that spread online implies — it isn't, and Mozilla's own CEO now prefers "AI Controls" for that reason. Second, don't assume flipping the toggle resets your tracking identifiers; the retest found your Glean and legacy client IDs stay exactly as they were. Third, don't treat Mozilla's self-reported adoption numbers — roughly 1% of users disabling all AI and 3% disabling individual features, per the CEO's August 25 essay — as independent proof of anything, since those figures come from the same telemetry system under scrutiny. Fourth, don't confuse Mozilla's ad partnerships, including a DNS prefetch to a Temu affiliate tracker, with "AI" — they're a separate revenue system that runs regardless of your AI settings. Fifth, if reducing what Firefox reports is actually your goal, go straight to about:preferences#privacy instead of AI Controls; that's the setting built for it.
Tools that make this easier
None of this requires new software, just knowing where the actual controls live. If you'd rather run AI locally in the browser instead of relying on a vendor's server calls at all, my WebLLM breakdown covers a genuinely local, in-browser inference option with a different privacy shape than any built-in browser chatbot. If your goal is less AI noise in your feed generally rather than in your browser settings, this Safari extension that hides AI-labeled YouTube videos is a smaller, single-purpose example of the same idea. For the broader habit of checking a viral claim before repeating it — the same method I used here — see the AI productivity illusion and my honest review of AI programming, both cases where the popular version of a story didn't match the sourced data. I used the same verification approach on AI data centers driving up power bills, another story where the national headline hid a lot of local variation. And if you're deciding which AI tools are worth your data in the first place, free AI tools worth using and AI tool ratings are the place to start before you grant any of them more access.
My take
Firefox's AI switch is off, and telemetry isn't — but I don't think that makes AI Controls worthless, just mislabeled by reputation rather than by Mozilla's own copy. The toggle does exactly what Mozilla says it does: it blocks generative features, and it's gotten measurably better at reducing first-launch network chatter, from 25 hosts in March to 14 by September. What it was never built to do is cut telemetry, ad-network calls, or the identifiers that tie your profile to Mozilla's servers, and a browser called "privacy-first" building a switch that sounds like it does more than it does is a real problem, not a technicality. If you actually want less data leaving your browser, use both settings — AI Controls for generative features, about:preferences#privacy for everything else — and don't assume one covers the other.
Frequently Asked Questions
Does turning off Firefox's AI features also stop Mozilla's telemetry?
No. A Firefox 155 network test found identical telemetry — 9 TLS hosts and 14 POST requests to Mozilla's telemetry server in a 120-second idle window — whether "Block AI enhancements" was on or off. Telemetry is a separate system with its own setting.
What Firefox version do I need for AI Controls?
Firefox 148 or later. It rolled out February 24, 2026, and the current version as of this test, Firefox 155, released September 1, 2026, expanded it to eleven preferences.
What exactly does "Block AI enhancements" turn off?
The sidebar chatbot, AI tab groups, link-preview summaries, PDF alt text, translations, Smart Window, and any extension using Firefox's built-in AI models, plus pop-ups promoting those features. It does not touch telemetry, ad-network requests, or tracking identifiers.
Does the switch reset my Firefox tracking ID?
No. Independent testing found the Glean client ID, legacy telemetry client ID, and profile-group ID stayed identical whether AI features were blocked or left on. Only a fresh, separate profile changes those.
How do I turn off Firefox telemetry, since AI Controls doesn't?
Go to about:preferences#privacy and uncheck every box under "Firefox Data Collection and Use," then restart the browser. That's a different settings section from AI Controls, and it's the one that actually reduces what Firefox reports.