just to clear somethnig up, (help)

Hopefully someone can help me, So My gf drives a 90 Teg LS Automatic, and recently she was driving and the engine light came on and the engine quit, and then she would wait about 2-5 min on the side of the road and it would fire up again and run fine for about 10-15kms and do the same thing. So, I checked the ECU for codes, and it appears to be flashing codes 4 (4 quick flashes) and 15 (Holds one flash, 5 quick ones) i know what those codes are, but this is where i need the help, cuz i drive an eg hatch (obd-1) and when it flashes say code 43 the light like holds 4 flashes then gives 3 quick ones, so is what im seeing (Holds one flash, 5 quick ones) a code 1 and 5 or a 15? Thanks alot for your time. EG.OB