LG OLED TV F21 Error Code Fix (No-Nonsense Guide)

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What This Error Means

F21 on an LG OLED TV means an internal panel/power drive fault. The TV has detected it cannot safely power or control the OLED panel, so it shuts down and throws F21 instead of starting normally. What you see:
  • TV clicks or shows the LG logo, then goes black and shows F21.
  • No picture, maybe sound for a second, then everything cuts.
  • Sometimes the standby light blinks and nothing else happens.
This is not a “wrong input” or “bad app” problem. It’s the self-diagnosis system saying something in the power chain or main board/panel communication looks wrong and the set is locking itself out to avoid damage.

Official Fix

The manual path is dull, but run it in this order before you spend money.
  • Hard power reset
    • Turn the TV off and unplug it from the wall.
    • Wait at least 60 seconds.
    • While it’s unplugged, press and hold the power button on the TV (not just the remote) for 10–15 seconds if your model has one.
    • Plug it directly into a known-good wall outlet (no power strip, no surge protector) and power it on.
    If F21 clears and the set stays on, you’re done. If it pops right back, keep going.
  • Kill everything hanging off the TV
    • Unplug every HDMI device, USB stick, soundbar, and antenna/cable feed.
    • Try to power the TV on with nothing connected.
    If a bad device or HDMI surge took the TV down, it sometimes lets the set boot once you disconnect the mess. If F21 still shows with nothing attached, the fault is inside the TV.
  • If you can reach the menu, do the software stuff
    • Press Settings on the remote.
    • Go to Support > Software Update and install any pending update.
    • Then run any built-in self test: Support > OLED Care / Self Diagnosis (names vary by year).
    • After that, do a factory reset: All Settings > General > Reset to Initial Settings.
    If F21 was a firmware glitch or a bad setting, this usually clears it. If it returns immediately after a clean reset, assume hardware.
  • If it never gets past F21
    • Listen for repeated clicking from the back of the TV when you try to power it on. That’s the power board trying and failing to start.
    • Check for any burnt smell or visible scorching through the rear vent holes. Do not keep forcing it on if you smell burning.
    At this point, the official fix is not a “button combo”; it’s board-level repair.
  • What LG officially wants you to do
    • Write down the model number and serial number from the back of the TV.
    • Note exactly when F21 shows (immediately, after logo, after a few minutes).
    • Contact LG support or an authorized service center and give them the F21 code.
    • They will typically test the power supply board and main board, then replace whichever has failed. On some sets, panel-drive faults can also mean the OLED panel itself is bad.
    If the TV is still under warranty, stop here. Do not open the back; let LG handle it so you don’t void coverage.

Is It Worth Fixing? (The Financial Verdict)

  • ✅ Fix: TV is under 5–6 years old, picture was perfect before F21, and a shop quotes roughly $150–$350 for a power or main board repair.
  • ⚠️ Debatable: Set is 6–8 years old or used hard every day, and you’re being quoted $350–$500, or the tech says it “might” be the panel but isn’t sure.
  • ❌ Replace: The OLED panel is confirmed bad, or the estimate is over 50–60% of the price of a new comparable OLED, or the TV is 8+ years old.

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