Gas engine kicks in unexpected on full charge (?!)

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Active member
Mar 23, 2018
Where we live, everything we need is within ~10-15km, so we almost never need/use the gas engine on our day-to-day driving. Car charges up fully overnight.

Then, like the subject line says, every now and then - maybe once every 4-8 weeks, totally out of the blue, and usually within 1km of leaving the house (fully charged), the gas engine will kick in.

Anyone else see this?

We're in a 2016 e-tron with the "Technik" trim level.
Not sure the specifics of your situation, but if you floor the accelerator you'll notice there's a bit of a little extra pressure for the last bit. When you hit that the car will go to boost mode, both battery and gas engine will be engaged for maximum acceleration.
if you're not accelerating hard and the gas kicks in that's a bit unusual -you have the car in EV only mode? (the default it starts on when there is charge).
Mine does this occasionally - plenty of charge in the battery but the ICE start itself. If I notice straight away I can't switch back to EV, the option is not available, after a minute or so the option becomes available again and I can switch back to EV though.

My guess is that it is some sort of ICE maintenance mode if it hasn't run in a while.
When the ICE first kicks in you'll see a little white EV symbol with a stroke over it near the top of the dash. That stays on until the engine is warm, and as you noted you cant force it to go back to EV mode. That took me a little while to figure out, but it's by design.
It does specify in the manual that for unspecified reasons, sometimes the ICE will have to run. As someone else said, I assume it's to do various things to keep the engine ready and clear from damage.
lozzd":2megk1q1 said:
It does specify in the manual that for unspecified reasons, sometimes the ICE will have to run. As someone else said, I assume it's to do various things to keep the engine ready and clear from damage.

Yeah, Chevy Volts will do this. I suspect that if the car runs for so long without the ICE running, it will force the ICE to run to prevent future problems.
Curious to know if your issue has arisen as your etron has aged. I have the same problem, the car unexpectedly changes from EV to hold battery mode, usually when going up even a slight hill or when accelerating from say 70 to 75 mph, and often when it is cooler (but not necessarily cold) outside. This essentially never happened during the first 45k on the odometer, but now at 4 years and 50k miles, it is happening all the time. Time for a trip to the dealer. Anyone else have this experience?
My 2016 with only about 26,000 miles has started this very thing. When going up a mountain road at about 35 miles per hour with 7 or 8 miles of charge left the ICE kicks in with the inability to put it back on E mode for a minute or so. Has just started doing this. Anybody have any info?
Trip #1 to the dealer on this problem: diagnostics revealed a jammed coolant valve which had to be replaced under warranty. Supposedly malfunction of the valve caused the car to revert to "limp" mode. Unfortunately this fix this did nothing to correct the problem and I'm heading back to the dealer for another go... will post an update later.
Trip #2 to the dealer revealed "nothing wrong" with battery or car

Puzzling that from 2016 to 2020 the car NEVER ONCE spontaneously flipped from EV to ICE (unless flooring it, forcing sport mode), regardless of hot/cold weather, regardless of flat or incline driving.
At 50k miles starting 2020 and driving exactly the same routes it flips from EV to ICE repeatedly. Painful... not really an EV anymore.
Same here. 2016, 60k miles.
Our range has been 9 - 10 miles this winter. I am quite disappointed to now open a gas car with a very small tank. :|
I just had the same thing happening.

Temperature well within the -10C - +40C range, battery fully charged, speed way below 130 kmph, no Sport mode, no kick down, I was driving in EV mode and all of the sudden, after a minute of driving, the ICE kicks in. So weird. Also got the impression the torque was down, as if ONLY the ICE was up...

After a moment I can go back to EV, but the ICE kicks in again after a few minutes. What's happening...
I posted the following a few years back.


The owner's manual mentions that the EV-only mode might not be available when the system decides that the engine must be run for mostly undisclosed technical reasons.

The one reason it gives is that the engine may need to start to get rid of condensation. The manual doesn't say where in/on/around the engine this troublesome condensation may be located.


Has it been very humid in your area lately? When I had my BMW i3 REX it also exhibited this behavior. It wanted to run the engine occasionally to lubricate the ice’s moving parts and to dry it out by warming up.
I've experienced this frequently this winter. It happens when the battery is cold (and now in its 6th year of age) - it can't crank out enough amps required to meet the acceleration required, which most often happens on an inclined road.

The control logic basically sees the user asks for more power than the battery can deliver (no matter how "full" the battery is), and hence the ICE kicks in. Even if I try to keep the power need well within the "efficiency" zone.

Cold batteries are known to be unable to provide high amp outputs. And the older the battery, the worse it gets. I don't get zippy acceleration in cold conditions.

With warmer spring weather, it doesn't happen anymore and my range on battery increased again to fully cover my daily commute (and more zippy-er acceleration again also).

Pity my battery pack wasn't replaced/renewed at the battery pack recall issue. On the other hand - my overall mpg is 70 and I still run 75% of the miles on battery power.

I have been considering adding a heating wire to the battery pack (powered by the charger)- so the pack is kept at 80F / 25C to avoid suffering a cold battery. But I'm a little hesitant to mess around with the 400V battery pack. I often wondered if this is done by any EV manufacturer to combat the dreaded cold battery issues. Anyone?