To get back to this issue... in case your engine is continuing to run and this is an issue of a Fuel Maintenance Mode gone awry, there was a posting a couple of years ago where a forum member could not make the FMM end. Suspicion was that on day 1, when the "Time for an FMM, start it now Y/N?" message appeared on the center console touch screen, he responded No (or just ignored it and the message went away), and then went to the gas station and added more gas, thinking he could avoid the FMM altogether by doing that... except that once the program displays the message, it’s too late to avoid it... The following day the FMM started, and now there was more gas in the tank... You need to Start the FMM before you can END it by adding gas.I have been using the gas because it hasn’t been going on battery and I’ve used several tanks. How do you get it out of fuel maintenance mode? I can try running it down again and only putting a gallon or so in it but I’ve sort of already done that
This member resolved the issue by a trip to the GM service department, where they were able to reset the FMM counter in the programming (apparently it actually counts the "average gas age" by days until the count reaches day 365, which then triggers the message to run the FMM).
IOW, if your Volt’s engine is continuing to run all the time, the GM service department can check to see if the FMM "clock" is reading day 365 or greater, and if so, can reset it.
You DO turn your car off when getting gas, don’t you? As MikeBCo mentions, another forum member in the past year or so failed to End the FMM because he left the car running when adding more gas (so the car didn’t go through certain system checks that happen upon shutdown/startup). When he turned the car off, then added more gas, and then restarted it, the FMM was ended.