Direct answer
For the LG M4 wireless OLED TV, output selection, mute/volume, format and the external audio path should be isolated. First, test TV speakers with a built-in app and PCM/stereo output.
What this covers
- LG M4 wireless OLED TV (OLED65/77/83/97M4*)
- Zero Connect box carries external video; isolate box/link versus panel/webOS.
- The specific fault this record addresses: has picture but no sound
What it does not cover
- ×The same symptom on a different LG product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
Audio output is routed to a device that is off or disconnected
What separates it No sound from the TV speakers, with an external audio device selected in the sound settings.
How to confirm Set the output explicitly to the internal speakers as a test. If sound returns, the fault is in the external path rather than the set.
- 2
The audio format is one the connected device cannot decode
What separates it Silence on specific apps or sources — typically Dolby Atmos or DTS content — while others play normally.
How to confirm Set the output format to PCM or Stereo as a test. If sound returns, the format was the problem and the receiving device does not support what was being sent.
- 3
Bluetooth headphones are still connected
What separates it No sound from the speakers or the soundbar, with a pair of headphones powered on somewhere in the room.
How to confirm A television that auto-reconnects to previously paired headphones mutes its own output silently. Disconnect them in the Bluetooth settings.
- 4
The set is muted or volume is at zero on a second control
What separates it No sound with the volume apparently up, in a setup with more than one remote.
How to confirm Where a soundbar or receiver handles audio, the TV's own volume may be irrelevant and the other device muted.
- 5
The internal speakers or amplifier have failed
What separates it No sound from the internal speakers on any source and any format, while headphones or an external output work.
How to confirm This is the conclusion once routing, format and mute state are eliminated, and is a service repair.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- Whether the internal speakers are explicitly selected as the audio output.
- Whether silence affects every source and app, or only specific ones — the latter points at audio format.
- Whether any Bluetooth headphones are paired and powered on nearby.
- Whether a soundbar or receiver is in the chain with its own separate volume and mute.
Set the audio output explicitly to the internal TV speakers
ReversibleThis separates a set with no sound from a set sending sound somewhere you are not listening.
Set the audio format to PCM or Stereo as a test
ReversibleIf sound returns, a surround format was being sent that the receiving device cannot decode.
Check for connected Bluetooth headphones and disconnect them
ReversibleA set that silently auto-reconnects to previously paired headphones mutes its own output with no indication.
Check mute and volume on every remote in the chain
ReversibleWith a soundbar or receiver present, the TV's own volume may not be the one that matters.
Confirm sound on a built-in app before blaming an external device
ReversibleA built-in app bypasses the whole HDMI chain and isolates the set itself.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- OLED65/77/83/97M4*. Zero Connect box carries external video; isolate box/link versus panel/webOS.
- Panel
- 2024 OLED evo with a Micro Lens Array (MLA) panel and the Alpha 11 processor — essentially the G4 panel. Self-emissive, so bright-window dimming is the Auto Brightness Limiter, not a backlight.
- Zero Connect wireless box
- This is the defining difference: video and audio reach the panel WIRELESSLY from a separate Zero Connect box that holds the ports (three HDMI 2.1 sockets). A 'no signal', dropout or lag fault is very often the box's placement or line of sight to the TV, not the source — keep the box within sight of the panel and clear of obstructions before troubleshooting the input.
- Smart platform
- webOS 24 with the Magic Remote; updates at Settings › Support › Software Update, screen share via AirPlay 2 and Miracast.
- Gaming / HDMI
- Up to 144 Hz with VRR, ALLM, G-Sync and FreeSync — but through the Zero Connect box's three HDMI 2.1 ports, and subject to the wireless link. A signal problem is the box or the wireless path first.
- Symptom boundary
- This record covers LG M4 wireless OLED TV when it has picture but no sound. A different symptom on the same hardware, or this symptom on a different LG product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !Unplug for a burning smell, distortion accompanied by heat, or visible damage at the rear panel.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. LG Support publishes this as "TV and home theater support". Official LG television manuals, webOS support, diagnostics and repair entry point. What that article does not carry is the model boundary — it is written for a product line, and OLED65/77/83/97M4* is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
My LG M4 keeps losing signal or looks laggy.+
The M4 sends the picture wirelessly from its Zero Connect box to the panel, so the first thing to check is the box: it must be within line of sight of the TV, within the stated range, and clear of obstructions and interference. Reposition the box and confirm the wireless link before you suspect the console, PC or cable — the sources plug into the box, not the TV.
How many HDMI ports does the LG M4 have?+
Three HDMI 2.1 ports, all on the Zero Connect box rather than on the TV itself. Everything connects to the box, which then transmits to the panel wirelessly, so port and signal troubleshooting happens at the box.
Sound works on some apps but not others.+
That pattern almost always means an audio format problem rather than a hardware one. The silent apps are likely sending Dolby Atmos or DTS that something in your chain cannot decode. Set the TV's audio output format to PCM or Stereo as a test — if sound returns, that confirms it.
The TV suddenly has no sound at all.+
Check whether a pair of Bluetooth headphones is powered on somewhere in the room. Televisions silently auto-reconnect to headphones they have paired with before, and when that happens the set mutes its own speakers with no on-screen indication at all.
Does this answer apply to every LG model?+
No. It is scoped to OLED65/77/83/97M4*. Zero Connect box carries external video; isolate box/link versus panel/webOS.
What should I record before troubleshooting no sound or audio?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing no sound, audio. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Stop for electrical noise, heat, sparks or repeated receiver protection.
Answer for the exact device and software version shown above.