Here's the GCODE script I used on my SV04 for PID auto-tuning. For best results, you want to print this directly from a SD -- Octoprint complains about lost connections when doing the actual PID tuning.

Some notes:

1. If you want to adapt this to a SINGLE extruder, delete everything related to extruder 2 -- hopefully from the code itself and the comments it's obvious what should be removed.
2. This is going to be slow. That is intentional. If you want to speed things up, here are a few things to try to search and replace "M303 C30" and change to "M303 C15" or "M303 C8" -- this will reduce the number of PID tuning cycles from 30 to 15 or 8 respectively.
3. I also included MPC tuning but that appears to be disabled in SV04 firmware. Errors about M306 not recognized are expected. If you've done a custom firmware build with MPC enabled, I'd appreciate any feedback.

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G28; autohome
G0 Z20; lift Z to 2cm
G27; park tool heads
M501; load settings
M155 S2; Temperature report every 2 seconds
M75 "PID tuning"; Start the print timer
M73 P0; % complete = 0 (P0)
M118 E1 Pn1 "Starting hotbed PID tune";
M303 C30 E-1 U1 S85; Bed, target 85 deg C
M118 E1 Pn1 "Saving hot bed PID results";
M500;
M73 P20; 
M118 E1 Pn1 "Starting E1 PID tune";
M303 C30 E0 U1 S240; Left extruder, target 240 deg C
M73 P40; % 66% complete
M118 E1 Pn1 "Starting E1 MPC tune";
M306 E0 T;
G27;
M500;
M118 E1 Pn1 "Saving E1 tuning results";
M500;
M73 P60
M118 E1 Pn1 "Starting E2 PID tune";
M303 C30 E1 U1 S240; Right extruder, target 240 deg C
M73 P80;
M118 E1 Pn1 "Starting E2 MPC tune";
M306 E1 T;
G27;
M118 E1 Pn1 "Saving E2 tuning results";
M500;
M77; Stop the print timer