Will cause evap related CEL but not limp mode, and won’t be instantaneous upon start up immediately after fueling. Again, have you tried driving to gas station shutting off car —- not fueling just sitting for five min—- then starting. Is this really fueling up related?
The system performs a self-check at ignition on. If there's a vacuum leak then the EML will be on straight away.
Fascinating, is it related to the degree of evap leak? if I start my car with the gas cap off there will immediately be a cel, and it will go into limp mode? Once I didn’t put the cap on snugly enough, took a while and CEL came on. Car ran perfectly despite the CEL. Code was related to evap leak. Unfortunately my car is still a day of work away from starting (two weeks of life) or I would try it today.
