Here is the information you need to read error codes on 92-95 Civic and Del Sol (CRX). Those cars are OBD-I, so the same info should be usable for any other OBD-I Honda. I have not had interest in other Honda cars, so I don't know what year Accords and Preludes are OBD-I.

Anyway, off to instructions.

There is a 2-pin (most likely green in color) connector by the ECU or somewhere under the passenger's side dash. It's a Data Link Connector. Connect it's two pins with a piece of wire. Watch out not to get jolted while you're connecting the pins.

You will read error codes on the gauge cluster, on the Malfunction Indicator Lamp. Turn the key to position "II" and watch the lamp blink. Error codes are reported by a number of blinks.

There are short and long blinks. Long blinks mean 10, and short blinks mean 1. For example, if you get "long-long-short-short-short", it means error code 23. There is a short pause between each flash (long or short) and a long pause between 2 error codes. There will always be long flashes before short flashes. So you cannot expect number 23 to be reported as "short-long-short-long-short".

Take note of all error codes reported by ECM (Electronic Control Module). Find a list online that explains "OBD-I error codes honda" and you will find out what your problems are.

Do not forget to remove the wire from the 2-pin connector once you are done.