2012 Lincoln MKX and this is in Florida, so I don't think we have a winter mix for gas. A very short time after filling up, the check engine light came on. Stuck a code reader on it and all four O2 sensors were reading rich. Called the gas station and verified that they were only using 10% ethanol. This condition kept up for about 10 miles and the check engine light went back out. The only thing I can think of that makes sense is that I got a blob of additives that wasn't mixed well into the gas, and might have been denser than the gas, so it got to the pump first. The store shouldn't have a tank problem .... brand new place, only been open 4 months or so. Topping off the tank with a couple gallons ethanol-free gas this morning for insurance. Any other ideas out there?
Could it be as simply as not having the gas cap tight after refueling? That has happened to my wife before
I would think the fuel would be pretty blended with the ethanol by the time it reaches the station.... no?
This is the new cap-less system. I did think of this .... pulled into another gas station, just to stick the nozzle in and take it back out. I couldn't press on the metal lid either way ... it was tight.
my truck would do this if I used a different station other than my reg. one, the light would go off on it's own... done the gas cap thing also.
I agree that ethanol should be mixed well prior to pumping it. I would think the specific gravity would be lighter than gas, too, making it float on top. There are other additives that go into the gas, and perhaps heavier, making them get picked up by the pump first. What also makes sense to me is that running the car for 10 miles, the fuel pump would mix the gas up well if it returns the excess fuel to the tank. This car is not made to take flex fuel ... 87 octane and max of 10% ethanol. Whatever happened made all 4 sensors freak out at the same time. It may just be calibrated pretty tight due to the restricted fuel requirement. Another idea ... the additive in the 4 gallons of fuel in the tank not mixing well with the additives in the 12 added to it. Sounds like it mirrors Frank's experience. I did top off with a couple gallons of ethanol-free gas and ran through the whole tank yesterday without any more drama. I don't think I will be using that gas station again.
Hey all, As a follow-up on this, I was just reading that this can happen if the Vapor Canister Purge Valve sticks open. Fumes from the tank are free to mess up the mixture. $12 part. I found this out, reading about a Ford Explorer doing the same thing. The part is just under the engine cover. I have had the same code happen at random times lately, but at first, it was just tied to fill-ups. It was stated that this can happen if you really fill the tank and the fuel warms up after being underground and cool. Which kind of fits. Now happening at random as the part gets worse. My next plan of attack is to bang on the engine cover and see if the check engine light goes off. Or maybe catch some air going over railroad tracks ... the hard landing ought to jar some things ... Lol (kidding!)
The gas cap is part of the vapor purge system. My Chrysler 300 has had the check engine light come on sporadically ever since the car was a month old, going on 10 years now. The service manager at the stealership said not to worry about it unless it stays on for a week or more. Mine always shows a lean condition on one side of the engine or the other, comes on once every few months. At least I know the light bulb works. LOL
