First, you should put the ECU in diagnostic mode and read what the code is. Assuming you have a 93 240 like is your listed car in your profile, and it hasn't had an engine swap, Its OBD1 so its not quite as easy as an OBD2 car, but not bad. You'll have to pull the passenger side kick panel out and turn a screw on the ECU to diagnostic mode. Key-on the ignition and count the blinks at the check engine light or on the ECU itself.
Here's a list of fault codes and how to read them:
https://www.240sxmotoring.com/ecu-fault-codes/
Generally EGR delete shouldn't throw a CEL.