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Mike V.
Mike V., Auto Service Technician
Category: Car
Satisfied Customers: 23624
Experience:  25 years of experience, Certified Subaru Technician and Nissan factory trained.
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1998 cadillac deville: gas cap..light came back..check engine light

Resolved Question:

I have a 1998 Cadilac Deville, the check gas cap light keeps coming on, I have tried several gas caps and was told to replace the filler tube which I did, 3 days later the light came back on and of course the check engine light too. I had it shut off but the next day, back on again, this is driving me nuts? Any ideas?
Submitted: 8 years ago.
Category: Car
Expert:  Mike V. replied 8 years ago.
Hi there!What code are you getting on the check engine light?
Customer: replied 8 years ago.
I don't know the exact code but it had to do with emissions, if this isn' sufficient I could go have them check again tomorrow.
Expert:  Mike V. replied 8 years ago.
OK.I am going to go out on a limb here.You need to have it smoked.This is the only way you can be sure where the leak is coming from.The code you are getting is likley a gross evap leak code.This means something on the evap system is wide open and the ecm sees it.Normally this code comes up when you leave the gas cap loose or off.It does however happen when the vent control valve is stuck open.The out on a limb part here is that I am not sure if the caddy has a vent control valve.If you have it smoke checked and they find no leaks at all then you will have a faulty pressure sensor.This sensor reads the pressure in the tank and opens valves to allow the pressure to bleed into the charcol canister to be stored and used later.If the pressure doesn't build up,the car knows there is a leak somewhere and throws the code.If you want to keep your sanity,pay to have the evap system smoked,then do the repair yourself.It will save you some money because you will be replacing the correct part.Hope this helps!Thanks
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Customer: replied 8 years ago.
That answer is Greek to me however I will take it to my mechanic today and get back to you,thanks for your help so far.

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