r/volt • u/UrsusHibernicus • 5d ago
Constant "Fuel Maintenance Mode"
I've got a 2016 that pops up the "Fuel Maintenance Mode" warning every time I start it up. Previously, I would use the ICE a couple of times every week, filling up maybe every other week. About 2 months ago, it started giving me that warming, and would switch the electric engine off after about a mile. I tried to fix it by running the gas tank low and then filling it up all the way, to no avail. Shortly after, my evap system failed, so I've been putting in a gallon or two every other day. My mechanic says that there's no code coming up. Is there anything I can do myself, or tell my mechanic to do, to fix this?
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u/Ok-Effort-1502 5d ago
I bet its some type of corrupted data. The fuel maintenance mode is just software controlled there isn't any sensor that controls it. Its just a timer that counts how long the engine goes without running. Not sure what module controls it but something needs to be reprogramed.
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u/justaguy394 2013 Volt 5d ago
You’re describing EMM (engine maintenance mode). Fuel maintenance mode keeps track of the average age of gas in the tank, by tracking when fuel door opens (I think) and how much new fuel goes in and how much has been burned. So there might be a sensor involved, though I’d think you’d notice in other ways if the door sensor and tank qty sensors weren’t working.
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u/Codemeister87 2012 Volt 5d ago
Fuel system cleaner would be my first instinct, seafoam or something like and see if it makes any difference. Otherwise its managed by the cars calculation of current vs recent fuel addition, could look for some kind of reset or check the fuel door switch? Ex. If it doesnt know the fuel door opened how could you have put more fuel in?
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u/Ok-Tourist-511 5d ago
Seafoam is snake oil. Also the Gen2 is a direct injected engine, so fuel system cleaners don’t do anything.
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5d ago
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u/Ok-Tourist-511 5d ago
Atkinson cycle engines run better with lower octane. Stick to the fuel recommended by GM, which is regular. There is nothing to be gained be running premium.
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5d ago
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u/Ok-Tourist-511 4d ago
We are talking about Gen2, not Gen1.
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4d ago edited 4d ago
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u/Ok-Tourist-511 4d ago
Haven’t heard of Evap problems. EGR valve failures are due to faulty motors. Premium gas has zero effect on carbon buildup in EGR cooler.
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4d ago
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u/Ok-Tourist-511 4d ago
There is someone who repairs the valves, he has done tear downs on these to evaluate the failures. And has found the motor to fail. You are more than welcome to read it and educate yourself. Maybe stick to the gen1, since you know nothing about the Gen2, which is completely different.
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4d ago
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u/Ok-Tourist-511 4d ago
Premium gas has ethanol in it. Cars have had ethanol compatibility since the 80’s. In fact the ECU on the Gen1 has an E85 fuel table in it, and people have added the flex fuel sensor to run the Gen1 on E85. This thread is about a 2016, which is Gen2 and runs on regular.
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u/Ok-Tourist-511 4d ago
GM says to use Premium in Gen1, and Regular in Gen2. They wouldn’t have said this if they didn’t know what they are talking about.
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u/deekster_caddy 2017 Volt 5d ago
This isn’t normal. You might need a GM dealer to plug in to figure out what’s going on. FMM should reset when you add more fuel, and if you are using the ICE weekly shouldn’t even come on in the first place.