What is error code 03130031-2f26 on ipf8400 - Canon iPF700 InkJet Printer

You replaced the "ink cartridges". It needs a "Maintenance cartridge". This is a separate cart, that holds waste ink.

Hi
"VHT leak detection error of left printhead,
in case of VHT exceeds rated value or falls
below the rated value."
So, error shows left printhead feeding voltage problem. It can be result of fault:
-printhead;
-Carriage relay board;
-flexible cable
-main controller.
Low speed of printing can be when printhead have overrange with it temperature; and when printing, printer makes a pauses to cold printhead. More information you can get from file PRINT INF under SERVICE MODE.
If you are a "ordinary user", looks like you can only try to change left printhead (success not guaranted!).

that number you wrote ;looks suspiciously like a hex a decimal value , for a ascII value , meaning it would appear to be coming from the front device , meaning print router or computer , when I have some brain teaser like this occur I break out the ole laptop and direct connect it from pc to printer via a cable (no wireless ) it eliminates any network or cable issues

This time you must comes up with Service Mode. This caused bypass your some problems.

It is a Controller-related error.

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www.usa.canon.com/cusa/support

Unplug external USB devices and wait for sometime,now reset our machine and access in safe mode, run Reginout Scan.