Maintenance and Service Guide

Mechanical
Fan error message - 90B
Table 8-51 Issues, possible causes, and xes
Items Procedures
Symptoms
Fan error 90B at boot
CAUTION: May lead to system
shutdown, data loss or possible system
damage.
Possible causes
Defective fan; out-of-date BIOS.
● The system fan is not spinning or not spinning properly (loose connection, fan is stuck
or defective).
● The temperature inside the case is too high, and the fan cannot spin fast enough to
remove the heat due to an obstruction to air ow.
Troubleshooting steps
General actions
1. Update BIOS and drivers (4. Update BIOS and drivers on page 85) or reset BIOS to
default. BIOS may implement new fan characteristics and updates for other
components.
2. Perform a hard reset (8. Hard reset on page 91). Performing a hard reset can reset
recorded thermal values in memory.
Thermal-related issue
1. Verify thermal condition:
a. Check fan and connection. Reseat fan cable.
b. Be sure that no obstructions or dust are in heat sink fan, n, or vent.
c. Test fan using HP PC Hardware Diagnostics (UEFI) tool (6. HP Hardware
Diagnostics and Tools on page 86). Be sure that the fan is not producing loud
noise and that fan blades spin correctly.
d. Test with a veried working fan.
e. Remove old thermal compound and pads, and replace properly with new pads.
2. Verify thermal solution
▲ Use Thermal Monitor tool (available only to authorized service providers/
technicians) to run stress test (processor and GPU) and verify that thermal
sensors are within limits after thermal condition is serviced.
Note BIOS currently omits fan presence detection to shorten boot time delay less than four
seconds. Therefore, the fan error is generated based on previous boot to operating system
that found system fan error.
Common issues and possible solutions 133