[89IROC&RS]

i know the codes cuz im a mechanic and have the book at work to decode them, im guessing most other people know them from experience. having to deal with the problems themselves. also, the code 42 is set by the computer when you set the timing on the car, because to do it right, you have to dissconect the timing sensor, a one wire connector near the passenger side firewall. try disconnecting the battery for ten seconds to clear all codes from the computer. and then drive it for a few days, and check the codes again, if you still get the code 42, then its more likely than not the electonic spark timing.