Does anyone know if the computer on the OBD II (96 Chev. Lumina, 3.1 engine) maintains trouble codes without throwing the Service Engine light coming on? My car sometimes runs a little rough but the Service Engine light hasn't come on. I just wondered if the OBD II stores codes for some problems and when it hits a threshold, it causes the Service Engine light to come on. I just thought about the O-2 sensor, etc. The car has 92k miles on it.
Thanks and I appreciate any thoughts on this matter.
David