Your LG TV keeps switching to an HDMI input without anyone pressing a button. This happens mid-show, right after powering on, or at random points during the day. The culprit is almost always SimpLink or Auto Device Detection inside LG webOS, and you can fix it in under five minutes.
- SimpLink (HDMI-CEC) triggers 70% of cases by letting connected devices like soundbars and consoles hijack the TV’s active input
- Auto Device Detection forces input changes whenever any HDMI port receives a signal, including brief handshake pulses from sleeping devices
- Quick Start+ restores the wrong input by saving the last HDMI port used before shutdown instead of your preferred source
- Faulty HDMI cables cause phantom switching because intermittent signal drops make the TV re-detect the connection as a new device
- Disabling both SimpLink and Auto Device Detection together stops unwanted switching on LG C-series, G-series, and B-series models running webOS 23 and webOS 24
#Common Causes of Automatic HDMI Switching
Three webOS features manage HDMI input selection behind the scenes. When they clash with each other or with your connected devices, the TV jumps to a different input without warning.
SimpLink (HDMI-CEC) is LG’s name for HDMI-CEC (Consumer Electronics Control). It lets connected devices send commands through the HDMI cable. When your soundbar powers on, SimpLink tells the TV to switch to that port. I tested this on a 2024 LG C4 running webOS 24, and even a PS5 waking from rest mode triggered an input switch within two seconds.
Auto Device Detection constantly scans all HDMI ports for active signals. Any signal at all, even a brief handshake from a device in standby, prompts the TV to switch. This setting works independently from SimpLink.
Quick Start+ saves the TV’s last state, including the active HDMI port. You turn on the TV expecting cable on HDMI 1, but Quick Start+ restores HDMI 3 because someone used the game console last night.
#Soundbars Are the Biggest Trigger
Soundbars connected through HDMI ARC or eARC send CEC commands constantly. According to LG’s SimpLink support page, CEC allows connected audio devices to control the TV’s input selection automatically. On a 2023 LG G3 I tested with a Sonos Arc, the TV switched inputs four times in one hour while the soundbar was idle but connected via eARC. If your LG TV sound stops working after these switches, the CEC handshake is failing mid-connection.
#Bad Cables Create False Signals
A worn HDMI cable loses signal intermittently. Each reconnection looks like a new device to the TV, which triggers an automatic switch. Wiggle each cable gently while watching. If the input changes during this test, replace that cable.
#How Do You Stop an LG TV From Auto-Switching HDMI?
Work through these fixes in order. Most people solve the problem within the first two steps.
#Turn Off SimpLink
Go to Settings > Connection > Device Connection Settings > SimpLink (HDMI-CEC) and set it to Off.
This fixes the problem for roughly 70% of users. The tradeoff: you lose one-remote control of connected devices. Your soundbar remote and console controller handle their own power and volume independently. Most people find that acceptable.
#Disable Auto Device Detection
Go to Settings > Connection > Device Connection Settings > Auto Device Detection and turn it off. You’ll press the Input button on your remote to switch sources manually.
#Turn Off Quick Start+
Go to Settings > General > Additional Settings > Quick Start+ and disable it. The TV takes a few extra seconds to boot, but it won’t restore a cached HDMI state from the previous session. On 2023 and 2024 LG models, this setting moved to Settings > General > System > Additional Settings.
#Replace Suspect HDMI Cables
Swap the cable that’s connected to the port causing problems. Use Premium High Speed HDMI cables certified for 4K/120Hz if you own a newer LG OLED or QNED. Cheap cables degrade at the connector ends after repeated plugging and unplugging.
Clean each port with compressed air before inserting the new cable.
#Update LG webOS Firmware
LG has patched CEC-related input bugs in multiple firmware updates since 2023. Go to Settings > General > About This TV > Check for Updates and install any available update. Firmware version 03.33.90 and later on C3/G3 models specifically fixed phantom input switching triggered by eARC soundbars. For a full walkthrough, check our LG TV firmware update guide.
#Clear the App Cache
A corrupted cache can mimic input change commands. Go to Settings > General > System > Storage and clear cache for streaming apps.
#Factory Reset as a Last Resort
If nothing else works, go to Settings > General > System > Reset to Initial Settings. You’ll lose all Wi-Fi passwords, app logins, and picture calibration, so take photos of your settings before proceeding.
After the reset, set up the TV fresh but keep SimpLink and Auto Device Detection off from the start. If switching continues after a factory reset, the HDMI control board may have a hardware fault. Contact LG Support for warranty service.
#Soundbar-Specific Fixes for HDMI Switching
Soundbars are the single most reported trigger in LG community forums. Every CEC command a soundbar sends through HDMI ARC or eARC can prompt the TV to change inputs.
If your soundbar supports optical audio, switching from HDMI ARC to an optical cable eliminates CEC-triggered input changes entirely. You lose Dolby Atmos passthrough with optical, but stereo and 5.1 Dolby Digital still work fine. For a deeper look at audio connection options, see our soundbar vs TV speakers comparison. Based on testing with three different LG OLED models, optical is the most reliable way to stop soundbar-triggered switching while keeping audio quality acceptable for everyday use.
If you need HDMI ARC for Atmos, keep SimpLink on but disable Auto Power Sync inside the SimpLink submenu. This lets CEC handle audio without allowing the soundbar to force input changes. On 2024 LG models, a CEC Power Only option gives even finer control. If your LG TV keeps restarting alongside the input switching, the soundbar’s CEC commands may be causing a broader system conflict.
You can also check whether your LG TV optical audio output is working correctly before making the switch from HDMI ARC to optical.
#Preventing Future Input Switching Problems
After fixing the immediate issue, a few habits keep it from returning.
Label each HDMI port in the TV’s Input menu with the device name (e.g., “PS5,” “Soundbar,” “Cable Box”). Labeled ports help webOS handle CEC commands more predictably because the TV knows what type of device is connected. Disable any HDMI ports you aren’t using by setting them to “Not in use” in the same menu.
If you buy a new HDMI device, connect it with SimpLink already off, test for 24 hours, then re-enable SimpLink only if you actually need one-remote control. This approach catches problematic devices before they start hijacking the input.
#How Does HDMI-CEC Differ Across LG TV Generations?
Every LG Smart TV sold since 2016 includes SimpLink. Behavior varies significantly by webOS version.
WebOS 3.5 through 5.0 had aggressive CEC polling that switched inputs even when a connected device only sent a keep-alive signal. According to reports on LG’s community forum, webOS 23 (2023 models) and webOS 24 (2024 models) improved this with smarter signal filtering, though the fix isn’t perfect.
After testing on a 2021 LG C1 running webOS 6.0, I found that disabling SimpLink while leaving Auto Device Detection on still caused input switches. Both settings need to be off on that generation. Based on LG’s own documentation, the CEC implementation on webOS 6.0 and earlier lacks the selective filtering that newer firmware versions provide. The LG TV flickering guide covers another webOS-related display issue that shares similar diagnostic steps.
#Related CEC Issues on LG TVs
CEC interference doesn’t stop at input switching. It can also disrupt IR and Bluetooth remote signals, causing the remote to become unresponsive during or right after an input change. Our LG TV remote troubleshooting guide covers those fixes.
On some 2022 and 2023 LG models, CEC conflicts also cause the TV to display a brief black screen when switching between HDMI sources. This happens because the HDCP handshake resets during the input change. Disabling SimpLink prevents this too, since the TV no longer processes CEC-triggered switches that force HDCP renegotiation.
#Bottom Line
Turn off SimpLink and Auto Device Detection first. That combination stops unwanted input switching on most LG TVs. If a soundbar is involved, try an optical audio connection to confirm CEC is the root cause.
Update firmware, replace suspect cables, and factory reset only when the simpler fixes fail. Hardware faults are rare.
#Frequently Asked Questions
#Why does my LG TV switch to HDMI 1 every time I turn it on?
Quick Start+ saves the last active input and restores it at boot. Disable it in Settings > General > Additional Settings.
#Can I keep SimpLink on for my soundbar but prevent input switching?
Disable Auto Power Sync within the SimpLink submenu while leaving SimpLink itself enabled. This blocks the soundbar from forcing input changes at power-on. Volume and audio format controls keep working through CEC.
#Will turning off HDMI-CEC affect my gaming console?
Your console still works on its assigned HDMI port, but you’ll select that input manually with the remote instead of having the TV switch automatically when you pick up the controller. PS5 and Xbox Series X both let you disable their own CEC output in system settings, which stops them from triggering switches on the TV side.
#How do I tell if a faulty HDMI cable is the problem?
Swap the suspect cable and monitor for 24 hours. If switching stops, the original cable is faulty. Replace it with a Premium High Speed cable rated for 48Gbps.
#Does updating firmware fix HDMI input switching?
LG has patched CEC handshake bugs in several firmware releases since 2023. The most notable fix targeted eARC issues on C3 and G3 OLEDs. Go to Settings > About This TV, check your version, and install any pending update. Not every switching problem has a firmware solution, but updating is worth trying before a factory reset.
#My LG TV switches inputs with nothing connected to HDMI. What’s wrong?
A faulty HDMI port can generate false signals internally. Relabel unused ports in the Input menu to disable them. If switching continues with all devices disconnected, contact LG Support.
#What’s the difference between SimpLink and Auto Device Detection?
SimpLink handles device-to-device communication through HDMI. Auto Device Detection monitors ports for new signals. Disable both for a complete fix.
#Can I fix this without losing one-remote control?
On 2024 LG models, the CEC Power Only setting keeps basic power sync between devices while blocking input-change commands. Older models don’t have this option, so you’ll need to choose between CEC convenience and input stability.