Sony Sony HT-S400 2.1-Channel Soundbar with Wireless Subwoofer AUTO STANDBY Error Fix: Unexpected Power Off / Auto Standby

Error code AUTO STANDBY on the Sony Sony HT-S400 2.1-Channel Soundbar with Wireless Subwoofer means: Unexpected Power Off / Auto Standby. The soundbar powers itself off unexpectedly during use, or turns off after a period when audio is very quiet or absent. Sony soundbars include an Auto Standby (auto power-off) feature that automatically turns the unit off after approximately 15 to 20 minutes of no audio signal input to conserve energy. This feature can be triggered unintentionally if the audio signal from the TV or source is very quiet, intermittent, or if the TV outputs silence between programs. Some Sony soundbar models allow disabling Auto Standby through a button combination or through the Sony Sound Connect app — consult the user manual for your specific model. If the soundbar shuts off during active audio playback (not silence), the issue may be a thermal protection shutdown — ensure the soundbar has adequate ventilation and is not in an enclosed shelf.

The most successful fix is "Improve Soundbar Ventilation and Check for Thermal Shutdown" (medium difficulty, ~30 minutes). Estimated DIY cost: $0-$10. HomeMD has 2 community-ranked fixes for this error.

This error is rated info severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Improve Soundbar Ventilation and Check for Thermal Shutdown") is rated medium difficulty and takes about 30 minutes. Tools needed: Soft brush, Compressed air canister, Soundbar remote control.

DIY cost: $0-$10. Professional repair typically costs $100-$160. Many homeowners save money by trying the top-ranked community fix first.

The Sony Sony HT-S400 2.1-Channel Soundbar with Wireless Subwoofer has 8 other known error codes, including: AUDIO DELAY (Lip Sync / Audio-Video Delay), BT PAIR FAIL (Bluetooth Pairing Failure), CEC CONFLICT (HDMI CEC / BRAVIA Sync Erratic Behavior), DISTORTED AUDIO (Crackling, Popping, or Distorted Sound), INPUT FAIL (No Audio from Selected Input Source), and 3 more.

Error code AUTO STANDBY also appears on 2 other Sony models: Sony HT-A5000 5.1.2-Channel Soundbar with Dolby Atmos and DTS:X, Sony HT-A7000 7.1.2-Channel Soundbar with Dolby Atmos and DTS:X. The fix may vary by model, so check each model's specific page for tailored repair steps.