What engine computer swap can you substitute for it?

You can use a rebuilt one but it has to program it to your car it has to be correct for engine/transmission etc.

Here are the engine computers you can swap for it.

P2P ECU - For the 2000 Honda Civic EX model with the D16Y8 engine, this is the standard ECU.
P2E ECU - For the 2000 Civic LX and DX models with the D16Y7 engine.
P28 ECU - A popular ECU for VTEC swaps and tuning for older Civic models (for OBD1 compatibility). However, you’ll need to convert your wiring from OBD2 to OBD1, which is a more involved process.

Let us know if you need anything else.