Cooling system error codes help identify failures in fans, pumps, sensors, radiators, thermal control circuits, and firmware‑based temperature protection. These codes may appear as on‑screen warnings, LED blink patterns, beep codes, or diagnostic numbers depending on the device or manufacturer. Errors shown before the system logo usually indicate fan or pump startup failures, while errors shown after the logo often point to temperature regulation, sensor faults, or blocked airflow.
Common PC Cooling System Error Messages
- CPU Fan Error — fan not detected, stalled, or below minimum RPM
- Chassis Fan Error — case fan failure or incorrect fan header
- CPU Over Temperature — heatsink not seated, pump failure, or thermal paste issue
- System Fan Failure — motherboard cannot read fan tach signal
- Water Pump Error — AIO pump not spinning or undervoltage
- Thermal Sensor Error — faulty or disconnected temperature probe
- VRM Overheat Warning — poor airflow around power delivery components
Liquid Cooling (AIO) Error Codes
- E01 — pump not detected or stalled
- E02 — coolant flow rate too low
- E03 — coolant temperature sensor failure
- E04 — coolant temperature exceeds safe limit
- E05 — USB or firmware communication error with cooler
- E06 — radiator fan failure or incorrect RPM
GPU Cooling Error Codes
- Fan 0/1 Error — GPU fan not spinning or tach signal missing
- Thermal Throttle Warning — GPU reaching throttle temperature
- Hotspot Temperature Error — uneven cooling or poor contact
- VRAM Overheat — memory modules overheating due to airflow issues
- Power Limit Thermal Trip — GPU shutting down to prevent damage
Server & Enterprise Cooling Error Codes
- FAN1/FAN2/FAN3 Failure — redundant fan failure detected
- FAN Redundancy Lost — system no longer has backup cooling
- Thermal Zone Overheat — rack or chassis zone temperature too high
- PSU Fan Failure — power supply cooling failure
- Airflow Obstruction — blocked intake or exhaust path
- Cooling Unit Communication Error — BMC cannot read cooling module data
Laptop Cooling Error Codes
- Fan Error — fan stuck, clogged, or tach signal missing
- Cooling System Failure — general cooling malfunction detected
- Thermal Shutdown — CPU/GPU exceeded safe temperature
- Heatpipe Failure — poor heat transfer due to damaged heatpipe
- Dust Detection Warning — airflow obstruction from dust buildup
LED Blink Patterns (General)
- 1 blink — fan startup failure
- 2 blinks — temperature sensor fault
- 3 blinks — CPU overheating
- 4 blinks — GPU overheating
- 5 blinks — cooling module communication error
Troubleshooting Steps
- Check all fans for movement and correct RPM
- Clean dust from heatsinks, radiators, and vents
- Verify pump operation on liquid coolers
- Reseat heatsinks and apply fresh thermal paste
- Ensure proper airflow direction in the case
- Inspect cables and fan headers for loose connections
- Update BIOS/firmware for cooling control fixes
- Replace failing fans, pumps, or sensors