Greg Peterson

Technical notes, mostly on CentOS and applications.
Feb 24, 2012

CentOS laptop temperature sensor

Fan error on boot

Today my ThinkPad X61 failed to boot. As the system came up, “Fan error” appeared in the upper left corner of the display, and then the machine shut itself off. It will boot if I press “Esc” at that time.

Package “lm_sensors”

I was worried about overheating, so I searched for a way to monitor temperatures. This package seems to work:

lm_sensors.i686 : Hardware monitoring tools

I installed it and then ran “sudo sensors” on the command line. The command showed some errors on STDERR, probably because there are no sensors for some measurements. Temperautres were okay, but the machine was still cool. It showed Fan 2 not running (0 RPM), which is bad news.

Fan connections

Following instructions in the X61 Hardware Maintenance Manual, I pulled out the battery and removed the keyboard. Fan 2 sits in the upper left corner as you look at the display. I traced the cables and tightened two screws a little.

With the keyboard still attached to the motherboard, I put in the battery and started the X61. Then fan began to spin, then stopped, and the machine booted with no error messages. I shut it down, replaced the keyboard, and booted again. No errors appeared.

Temperature monitoring

I ran “sudo sensors” on the command line again. This time it showed both fans running, and temperatures looked good. Now, after running several hours, installing some updates, and doing other normal work the STDOUT looks like this:

Adapter: Virtual device
temp1:       +47.0°C  (crit = +127.0°C)                  
temp2:       +39.0°C  (crit = +99.0°C)                  

Adapter: ISA adapter
fan1:       3414 RPM
fan2:       7449 RPM
temp1:       +47.0°C                                    
temp2:       +46.0°C                                    
temp3:       +46.0°C                                    
temp4:       +42.0°C                                    
temp5:       +32.0°C                                    
temp6:       +50.0°C                                    
temp7:       +30.0°C                                    
temp8:       +32.0°C                                    
temp9:       +46.0°C                                    
temp10:      +40.0°C                                    
temp11:       +0.0°C                                    
temp12:       +0.0°C                                    
temp13:       +0.0°C                                    
temp14:       +0.0°C                                    
temp15:       +0.0°C                                    
temp16:       +0.0°C                                    

Adapter: ISA adapter
Core 0:      +43.0°C  (high = +105.0°C, crit = +105.0°C)  
Core 1:      +44.0°C  (high = +105.0°C, crit = +105.0°C)  

Those temperatures look okay,