Display & Monitor Error Codes

Display and monitor error codes help diagnose problems with video output, signal detection, backlight failures, firmware issues, and panel electronics. These codes may appear as on-screen messages, LED blink patterns, beep codes, or diagnostic numbers depending on the manufacturer. Errors shown before the system logo usually indicate GPU or cable detection failures, while errors shown after the logo often point to firmware, resolution, or panel issues.

Common On-Screen Monitor Error Messages

  • No Signal — GPU not sending output, loose cable, wrong input source
  • Cable Not Connected — HDMI/DP/VGA unplugged or damaged
  • Out of Range — Unsupported resolution or refresh rate
  • — GPU sending incompatible signal
  • Power Save Mode — No active video signal detected
  • Check Video Cable — Cable failure or bent pins
  • DisplayPort Link Failure — DP handshake failed
  • HDCP Error — Encryption/authentication failure
  • Invalid Format — Corrupted or unsupported video mode
  • No DP Signal From Your Device — GPU not initializing DisplayPort

LCD / LED Monitor Diagnostic Codes

Backlight / Panel Errors

  • Dim screen — Backlight inverter failure
  • Flickering — Failing capacitors or unstable power rail
  • Bright spots — Damaged diffuser or LED cluster failure
  • Dark patches — Backlight zone failure
  • Vertical lines — T-CON board failure or ribbon cable damage
  • Horizontal lines — Panel driver failure
  • Ghosting — Slow pixel response or aging panel
  • Color tint — Incorrect gamma or failing LED array

T-CON Board Error Indicators

  • No display but backlight on — T-CON not receiving LVDS/eDP signal
  • White screen — T-CON power rail failure
  • Random colored lines — T-CON data corruption
  • Flashing screen — T-CON firmware instability

CRT Monitor Error Codes (Retro Systems)

Common CRT Symptoms

  • No raster — Flyback transformer failure
  • High-pitched whine — Horizontal deflection failure
  • Image collapse (vertical line) — Vertical deflection failure
  • Image collapse (horizontal line) — Horizontal deflection failure
  • Color bleeding — Aging tube or bad convergence
  • Purity issues — Magnetic interference
  • Screen blooming — Weak high-voltage regulation
  • Faded image — Tube wear or low cathode emission

CRT LED / Front Panel Codes

  • Blinking power LED — HV shutdown
  • Amber LED — Standby mode or no video signal
  • Red LED — Internal protection triggered

GPU-Related Display Error Codes

POST / Firmware Codes

  • 0xD6 — GPU not detected
  • 0x92 — PCI/PCIe initialization failure
  • 0xA0 — IDE/SATA OK, GPU next stage failed
  • 0xB2 — Legacy video initialization error
  • 0x99 — Super I/O initialization, GPU may be next failure point

Beep Codes

  • 1 long, 2 short — GPU failure
  • 1 long, 3 short — GPU memory failure
  • Continuous short beeps — PCIe power issue

Smart TV / Monitor Firmware Error Codes

Samsung

  • Blinking red LED — Power board failure
  • Error Code 6-1 — Backlight failure
  • Error Code 4-3 — T-CON communication failure

LG

  • Error 105 — Network firmware issue
  • Error 201 — HDMI handshake failure
  • Error 202 — HDCP authentication failure

Sony

  • 6 blinks — Backlight failure
  • 7 blinks — T-CON board failure
  • 8 blinks — Audio board failure affecting display

DisplayPort / HDMI Diagnostic Codes

DisplayPort

  • DP AUX Error — Communication channel failure
  • Link Training Failed — Cable or GPU handshake issue
  • HPD Failure — Monitor not detecting hot-plug signal

HDMI

  • EDID Read Error — Monitor cannot send display capabilities
  • HDCP Authentication Failed — Encryption mismatch
  • TMDS Clock Error — Signal integrity failure

Typical Causes of Display & Monitor Errors

  • Loose or damaged cables
  • Incorrect resolution or refresh rate
  • GPU failure or overheating
  • Faulty T-CON or panel electronics
  • Backlight inverter or LED array failure
  • Firmware corruption
  • Power supply instability
  • Aging CRT tube or capacitors

Troubleshooting Steps

  • Reseat HDMI/DP cables
  • Try another input source
  • Lower resolution/refresh rate
  • Test with another monitor
  • Update GPU drivers and firmware
  • Reset monitor to factory settings
  • Inspect for backlight or panel damage
  • Check GPU temperatures
  • Replace T-CON or power board if needed
Scroll to Top