Xavier not turning on Fan when CPU heats up. Has to be turned on via software

We have a Xavier sitting in the room running some light code, but the heatsink gets super super hot(70 + C) and the fan doesn’t turn on, unless we manually turn it on from software, even leading to it shutting itself off from overheating. I have checked the fan cable and it’s securely in there.

Has anyone else run into this issue and found a fix besides a script that checks the CPU temp and turns on/off the fan vs custom heat levels

There should be some thermal node that can be simulated as high degree. I am still checking how to clarify this issue.

Could you also dump below value when you said “temperature is high”?

root@jetson-0422418042099:/sys/kernel/debug/bpmp/debug# cd soctherm/
root@jetson-0422418042099:/sys/kernel/debug/bpmp/debug/soctherm# ls
bias_en  group_AUX  group_CPU  group_GPU  group_PLLX  oc  resume  sensor_params  sensor_params_raw  sensors  suspend  temp_sw_override  throttlectl
root@jetson-0422418042099:/sys/kernel/debug/bpmp/debug/soctherm# cat group_*/temp

Also, below method should enable fan,right?

sudo -s
echo 255 > /sys/kernel/debug/tegra_fan/target_pwm

I’ve resolved it by running jetson_clocks.sh which comes with it. Seems to turn on the fan at top RPM, and as I am currently working on it, I’m not inclined to let it get back towards the 85-90 degree C it was at before. Thank you though :)


I don’t think you should just call this as a fix. If your fan really cannot start to run under normal case (w/o jetson_clock.sh), it may be an issue.

The fan would start to run when the weighted average temperature of CPU,GPU,AUX thermzones (3:3:4) > 50C.

Thus, please share the degree you observed of these 3 during the normal test.

cat /sys/kernel/debug/bpmp/debug/soctherm/group_AUX/temp
cat /sys/kernel/debug/bpmp/debug/soctherm/group_CPU/temp
cat /sys/kernel/debug/bpmp/debug/soctherm/group_GPU/temp

I’m also having this exact same issue.

My system keeps freezing and crashing and I don’t see the fan ever turning on.

root@jetson-0423218011160:/home/nvidia# cat /sys/kernel/debug/bpmp/debug/soctherm/group_AUX/temp
root@jetson-0423218011160:/home/nvidia# cat /sys/kernel/debug/bpmp/debug/soctherm/group_CPU/temp
root@jetson-0423218011160:/home/nvidia# cat /sys/kernel/debug/bpmp/debug/soctherm/group_GPU/temp

@whoishoa, the temperatures you show are 44.5°C or 45°C, so the fan is not expected to turn on (as long as it keeps below 50°C, as said by @WayneWWW). Maybe your freeze and crash is related to something else.

We notice some issue for fan. Please follow up the steps in this thread.


The policy of fan running > 50C is for normal case. If you have problem as above thread, please let us know.