check engine light is on .had it diagnosted I was told the gas cap was causing problem,I changed cap and light is still on.
check engine light due to gas cap being loose or worn,is what i was told. on 1992 Lexus LS400
It takes two "drive cycle trips" to "turn off" the light. The computer looks at certain criteria before it will naturally turn off the light, if not a scan tool is required to turn off the light.
ventilation line restriction in gas line.