[Diabolis]

Maybe replace it with another O2 simulator that you can still get (at a reasonable cost to boot) like this - Lexus IS 300 O2 Sensor Eliminator MAGNUM EZ CEL FIX Oxygen Sensor Simulator (no personal experience or affiliation).

 

[Diabolis]

No, He has changed it. It has been a long time sense we talked. Any person who knows basic circuits. Should be able to fix it. It is very basic. Timer chip, resisters, and diodes.

Does that box have a 555 timer chip based circuit?