Creality Ender 5 S1 ABL problem

I am having a problem setting up my Ender 5 S1. When I preheat the nozzle and bed all seems OK but as soon as I send the ABL command, the nozzle temp resets to 0. See below.

Any suggestions?


Recv: T:200.38 /200.00 B:60.61 /60.00 @:55 B@:0 FAN0@:0
Recv: T:200.33 /200.00 B:60.55 /60.00 @:55 B@:0 FAN0@:0
Recv: T:200.33 /200.00 B:60.50 /60.00 @:55 B@:0 FAN0@:0
Recv: T:200.26 /200.00 B:60.48 /60.00 @:56 B@:0 FAN0@:0
Send: G29
Recv: T:200.26 /0.00 B:60.40 /60.00 @:0 B@:0 FAN0@:0
Recv: echo:busy: processing
Recv: T:200.10 /0.00 B:60.36 /60.00 @:0 B@:0 FAN0@:0
Recv: T:199.59 /0.00 B:60.23 /60.00 @:0 B@:0 FAN0@:0

Usually it is enough to preheat the bed for ABL, as the nozzle distance and therefor, preheating of the nozzle, is not required. In easy words. The sensor is not affected by the nozzle temperature and therefor the nozzle temperature is irrelevant.

I assume the ABL procedure in the firmware is addressing this in a stupid way as it ignores the current state. It turns the bed heater on (which you already did), turns the nozzle off, waits for the bed to reach temperature and starts probing.

However. There is no need to preheat the nozzle anyway. You preheat the bed before running ABL. The nozzle has a relative hot temperature and the fan is preventing not only heat creep, but also thermal expansion of the upper part of the hot end. The only part, where thermal expansion takes place is the hot end and that gets to temperature quite fast.

Pre heating is only required for the bed, as e.g. the bed screws get warm, change length and effect the bed position. That is why a short preheat phase before the first print is essential.

So just change your start code to turn on the nozzle heater after ABL is done and everything is fine and you save energy, too.