Faulty Fuel

I filled my tank the other day and drove 2 miles to work. On the way home, my check engine light came on. I took it to my local GM dealership to have it checked. The service manager reprogrammed the computer and sent me on my way. Two days later the light was on again. I took it back to the same dealer. The service manager called and said the ethanol level was at 30% and that triggered the light. He recommended the tank be drained and fresh gas at 10% ethanol be used. I paid the $93 for the draining plus 5 gallons of gas. My car is a 2007 Impala with a 3.5L engine which can use E85 gas. Was the draining necessary since the ethanol level was within tolerances? Why did the engine light come on just for that?

Because the Dealer needed $93…

Your vehicle is a Flex-Fuel vehicle which means it’s capable of using gasoline with a concentration of up to 85% ethanol content. As to why the dealer would drain the gasoline with a 30% ethanol content is beyond me as this shouldn’t cause a problem with the vehicle.

If we knew what codes were stored when the Check Engine light came on might point to what the real problem was. Unless I’m missing something here, what the dealer told you sounds bogus!


For $93 you could have bought a code reader, scanned the codes, and reset the light yourself…

My vote is with the others and I’m curious as to why you did not ask the service manager about your car being a Flex-Fuel model and then see what his response to that would be.

His response to that very question was that I didn’t drive the prescibed 7 miles after the fill-up, and that the gas I put in had a higher concentration of ethanol than what was already in the tank. The owner’s manual confirms that if ethanol levels are higher than what’s in the tank, the driver indeed needs to allow the computer to readjust to the variation by driving about 7 miles. I was also told the gas was “contaminated”, possibly by the winter mix of ice guard. Since he reprogrammed the computer once already, I figured the light would continue coming on as long as the gas was still in the tank. Chalk this one up to me being in a hurry to solve the problem. I guess I could have driven the gas out of the car with no damage.