Sonos Arc Ultra No Sound From TV: eARC Fixes That Actually Work

The Arc Ultra was fine last night. Tonight the picture's up, the Sonos app sees the bar, and there's nothing coming out of it. Or a slightly different version: sound plays, but Dolby Atmos has quietly disappeared and the app shows plain stereo PCM on content that should be booming. Both symptoms trace back to the same place, so it helps to understand what's actually going on before you start unplugging things.

The Arc Ultra has exactly one connection to your TV: the HDMI cable running from the bar to the TV's eARC/ARC port. Every time either device wakes up, the two negotiate a handshake over that link. The TV announces it wants to send audio, the bar announces what formats it accepts, and they agree on a channel. When that negotiation fails or half-completes, you get silence. When it completes badly, you get the fallback: two-channel PCM instead of Atmos. Arc Ultra owners have reported both on Sonos's own forums since launch, and a fair number of cases are the bar itself getting stuck rather than the TV. That's actually good news, because a stuck handshake is fixable in minutes.

Try this first: the ordered power cycle

Order matters here, which is why a quick remote-button off/on often does nothing.

1. Unplug the Arc Ultra from the wall. Unplug the TV too.
2. Wait at least 30 seconds. Shorter waits don't reliably clear the HDMI state on either end.
3. Plug the TV in first and let it fully boot.
4. Plug the Arc Ultra back in and give it a minute to reconnect.

This forces both devices to run a fresh handshake from zero, and for the common "Atmos vanished" and "bar went silent overnight" cases it works more often than any settings change. If the problem returns every few days, keep reading, because something in the chain is causing the renegotiation to fail.

If the power cycle didn't do it, check these settings

Work through them in order on the TV, since that's where most of the levers live.

1. Confirm the cable sits in the TV port labeled eARC or ARC, not a plain HDMI input, and that it's fully seated at both ends. Reseating fixes more than anyone likes to admit.
2. Turn on HDMI-CEC. Samsung calls it Anynet+, LG calls it Simplink, Sony calls it Bravia Sync. The audio return channel rides on CEC, so with it off the bar can sit silent.
3. Set the TV's eARC mode to Auto (on Samsung: Settings > Sound > Expert Settings > HDMI-eARC Mode). If your TV lets you toggle eARC off entirely, testing with plain ARC can tell you whether the eARC negotiation itself is the weak link.
4. Set Sound Output to the Sonos bar, not TV Speaker.
5. Set the TV's Digital Output Audio Format to PCM as a test. If sound comes back, the TV was sending a format the chain couldn't hold. Switch to Auto or Pass-Through afterward to get Atmos again.

The cable question

If dropouts are intermittent, suspect the cable before you suspect the hardware. eARC pushes far more data than old ARC did, and a marginal cable will pass a handshake one day and flub it the next. Use a short, certified Ultra High Speed cable. One note worth knowing: there's no such thing as an "HDMI 2.1 cable," whatever the packaging implies. Cables are rated by speed, and Ultra High Speed certification (48 Gbps) is the spec that matters for eARC stability.

Firmware, then the nuclear option

Update both sides. Sonos pushes Arc Ultra firmware through the app (Settings > System Updates), and TV makers ship eARC and CEC timing fixes constantly, so check for a TV update even if it "just updated." If the bar still won't pass sound, re-run TV Setup in the Sonos app with everything else disconnected from the TV. A factory reset of the bar is the last resort, and if a reset plus a known-good cable plus a second HDMI source still gives you silence, you're likely looking at a hardware fault. Test the TV's eARC port with another device if you can. A dead port points at the TV; a bar that stays silent on two different TVs points at the bar, and that's a Sonos support conversation, not another settings hunt.

About Atmos specifically

Lossless Atmos (TrueHD) needs eARC, full stop. Plain ARC can carry the compressed Dolby Digital Plus version, which still sounds very good, so if your TV only offers ARC you're not broken, just capped. And optical can't carry Atmos at all, which doesn't matter here anyway since the Arc Ultra's only TV input is HDMI. If the app shows stereo PCM on a Netflix Atmos title, that's the fallback handshake state, so start back at the top with the ordered power cycle. It's the fix this bar responds to best.