2003 Mercury Grand Marquis Check Engine Light

Did you check your gas cap? They do have a sensor that when not tightened down correctly will set off the check engine light.

I just got back from Auto Zone and it said the gas cap was what made the Check Engine light come on. I put some Vaseline on the rubber seal and i'm going from there. Eventually I will probably have to get a new gas cap.

Always make sure you get 3 to 4 clicks from the cap before sealing the door panel that should save you on the need to buy a new one.

My Grand Marquis only let's me do one click when putting the gas cap back on. The readout just said that there was a small vapor leak which is usually from the gas cap.

yes an if its a one click then somethings up with that particular cap. best replace with one ya know you can get more then one click out of.

I thought all Ford/Mercury/Lincolns at that time had the one click because my Grand Marquis always had it and my grandpa's Lincoln Town Car also has the one click. I was not aware that they sell caps that screw on and click more then once.

the one click is an after market put on by dealers an or rental car companys when the original is wore out or stolen.

My 2003 grand marguis service engine light came on today with 75000 miles I'm asking what could it be.My husband told my son to go turn the gas cap until it clicks and take the battery cable off count to 20...surprisingly it went off.

I was told my gas cap was the problem too and to just reseat it and the light would go out eventually but it has not. Can this cause severe mileage loss is there really is a Evaporator Canister leak, hose leak, or if the purge valve or vent solenoid has become defective? Thank you.