Looking for some advise. Yesterday when leaving a store apon startup my ses light came on and stayed on. After a couple of erands and what not it was still on. When I thought back through my day I had gone to a gas station with about 3/8 tank of gas left and took the gas cap off to refuel. The credit card system was down at the station and I went inside to use the restroom and see if they had an atm. Long story short I came out a couple minutes later and put the gas gap on without getting any gas. Fast foward to later in the day when I got home I re tightened the gas gap again. So went out last night and put about 80 miles on it and the light would not turn off. So this morning I went to auto zone and had the read the code. It said P0456 The ECM System has detected a large leak in the Evap system during a system monitor test. Probable causes are 1. Defective, loose or missing fuel cap. 2. Evap canister broke, hose cracked or not connected. 3. Purge or Vent solenoid defective. 4. Vacuum leak engine. So I went home and manually cleared the light per the gas pedal procedure. Now I put about 60 more miles on it and the light has not come back on. Should I still take it to the dealer? Does the light stay on sometimes like that for the gas cap on not shut itself off? If there is a major problem will it come back on again and does the system do self diagnostic checks frequently. Sorry for the long post any feedback is greatly appreaciated. Just trying to avoid an unecessary trip to the dealer.

 

Also does anyone know if the gas pedal procedure clears the stored codes or if the dealer can still find them? Thanks

 

i would take it to the dealership and explain the situation just to be safe, because in the long run, there might be a potentially bigger problem

 

I'd call the dealer and ask them... Just explain it to them. If you need to come in, they should be honest and have you come in. That is if you have a good dealer that cares.

 

Cool thanks for theadvise guys. I will call them first thing tomorow. Hope its nothing major.

 

ECU reset will erase the code and remove the SES light. Maybe you should do that, drive the car for 30-50 miles and (or sooner if it is a serious problem) and see if the light still comes on.

 

Ok thanks thats what I wanted to know DiamondGCoupe. I drove about 50 miles today and no light. Do you think if there is still a problem or a serious problem the light will come back on or does it only come on for a problem once within a period of time?

 

No. It most likely came on because of what you said before, therefore, if it's off now, no problems. It should have gone off after you fixed the gas cap but I guess not.