Multiplexer Error Code

[its_ish]

Hi, I have a EP3 with a built K24 engine with a Comptech supercharger.
I have this annoying problem with my Kpro intermittently throwing a 39-1 P0600 Multiplexer not present problem.
Can anyone please point me in the right direction as to what I can do to rectify the problem? I have to disable the
Multiplexer and with that, no aircon!
I have checked grounding, replaced the Multiplexer and still throws the same occasional Multiplexer error code.

[Spunkster]

HAve you followed the factory service manual (Helms) troubleshooting for this error?

[its_ish]

Ok will consult the service manual, but no other suggestions on what the issue might be?