OBDII is a US government mandated diagnostic system. The idea was that a standard on board diagnostic system would provide a means of monitoring emmissions critical components and overall system performance and provide a means to maintain these systems. By maintaining the systems, the theory is that more cars will be operating properly, thus creating lower emissions.
All cars delivered in the US from '96 on have this system as part of its computer system.
This system is part of the overall engine and chassis computer management systems and is not something that can be retrofitted.
In your '92, non US model you have a computer self diagnostic system of some description. You need to research this with a service manual to learn more about the specifics of your system. You will need a code scanner or computer software and a specific connector/cable to retrieve any error codes that may have been set. If an error code is set the check engine light will illuminate indicating that an error code has been "trapped."
Most commonly, if a code has been trapped, the problem is a sensor of some description. Of these sensors, the oxygen sensor is the most common sensor to fail.
Hope this helps,
BTW, I'm not currently experiencing insomnia, I am currently in Copenhagen, Denmark, so it is only an hour later than your local time. LB