Intermittent Failures
WARNING: This page is about a different car, the 1989 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
Intermittent failures may cause "CHECK ENGINE" light to flicker or illuminate and go out after the intermittent fault goes away. The corresponding trouble code, however, will be retained in control unit memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from control unit memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES section.