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I have two High Altitude 4xe Wranglers here in Michigan. Both of ours entered FORM mode around the same time. I was able to get both of them running like they were during warmer weather.

I took each one out for a drive running errands in Esave mode using the ICE and could get the oil and coolant temps up to around 190 degrees. When I got home I pulled the car into the garage with the back end outside the garage door and let it run for about 90 minutes with the temperatures getting up in the 205-210 degree range. I then switched it back into hybrid mode and took them for a quick drive while they were hot and both exited FORM mode and the message in the instrument cluster went away.

Both of our 4xe’s have been running the same as they were in the warmers month and haven’t received any messages in the past month.
 

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2021 Rubicon 4xe
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I have two High Altitude 4xe Wranglers here in Michigan. Both of ours entered FORM mode around the same time. I was able to get both of them running like they were during warmer weather.

I took each one out for a drive running errands in Esave mode using the ICE and could get the oil and coolant temps up to around 190 degrees. When I got home I pulled the car into the garage with the back end outside the garage door and let it run for about 90 minutes with the temperatures getting up in the 205-210 degree range. I then switched it back into hybrid mode and took them for a quick drive while they were hot and both exited FORM mode and the message in the instrument cluster went away.

Both of our 4xe’s have been running the same as they were in the warmers month and haven’t received any messages in the past month.
Yep, not that difficult.
 

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This is what Dan Fry posted on Facebook. This aligns with my own personal experience.

Cold Weather Operation of the Wrangler 4xe

Remote start and regular button start will both work, with an EVSE plugged in. That’s a great way to warm the battery and the cabin using energy from the wall. The Jeep will not shift out of Park until you remove the charge handle, to prevent accidentally driving off while plugged in. The plug icon in the cluster gives you a heads up.

You might see Fuel/Oil Refresh more frequently in cold weather. That’s because short engine runtimes in cold temperatures are most conducive to fuel dilution into the engine oil. If this happens, the solution is to get the engine warm and keep it running for up to an hour and a half to evaporate the fuel out of the oil… or change the engine oil.

Here’s what to expect as mornings get colder. All of this logic is true, whether an EVSE is plugged in or not:

Above ~32°F, and with sufficient battery and fuel, the vehicle will usually power up silently (ICE not running). The exception is if you have a very high HVAC demand.

Below 32°F but above 10°F, the ICE engine will also run at startup. You can select Electric mode to shut it off, relying instead on the electric heaters. There will be a range penalty. If you use remote start in a cold garage, take note exhaust will be emitted.

Below 10°F, the engine will always run until various systems are up to operating temperature. Electric mode will be unavailable during warmup. At these temperatures, the electric heater really isn’t an efficient way to heat the cabin, and your EV range would be greatly reduced by that anyway. The same is true of BEV’s, but they don’t have an ICE to help.

If it’s below ~5°F outside when you shut down, the instrument cluster will advise you to plug in an EVSE to maintain battery temperature. This is only strictly necessary in case the battery temp falls below -20°F overnight. Level 1 or Level 2 are suitable.

All the way down to -20°F, the Jeep can start unassisted (without an EVSE connected). This is the same capability as other Wranglers and most ICE vehicles.

If outside temperature is likely to fall below -20°F, you definitely want to connect an EVSE overnight. The Jeep will wake up periodically and warm and circulate coolant to facilitate a restart. It’s not necessary to also connect a block heater.

With an EVSE connected, the Jeep can start as low as -40°F. This is the same performance a other Wranglers and the best production ICE vehicles - they require block heaters in these temperatures.

Happy Snow-Jeeping! 🙂
 

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Now that it's cold here in Colorado, I see my 4xe using the engine almost all the time. I leave my ~32-40F garage on battery, and after a few minutes in the cold the engine starts and doesn't stop until I turn the Jeep off. Electric mode is "temporarily unavailable", though I saw it come back (and the engine stop) when the weather warmed up to just below freezing and I drove for a while.

Anyone know the actual rules for how the 4xE is supposed to handle cold weather? I really wonder why the engine needs to run at all, but I'm guessing there's a good engineering reason.
 

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Now that it's cold here in Colorado, I see my 4xe using the engine almost all the time. I leave my ~32-40F garage on battery, and after a few minutes in the cold the engine starts and doesn't stop until I turn the Jeep off. Electric mode is "temporarily unavailable", though I saw it come back (and the engine stop) when the weather warmed up to just below freezing and I drove for a while.

Anyone know the actual rules for how the 4xE is supposed to handle cold weather? I really wonder why the engine needs to run at all, but I'm guessing there's a angood engineering reason.


I’m
 

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2021 Sahara 4xe
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Now that it's cold here in Colorado, I see my 4xe using the engine almost all the time. I leave my ~32-40F garage on battery, and after a few minutes in the cold the engine starts and doesn't stop until I turn the Jeep off. Electric mode is "temporarily unavailable", though I saw it come back (and the engine stop) when the weather warmed up to just below freezing and I drove for a while.

Anyone know the actual rules for how the 4xE is supposed to handle cold weather? I really wonder why the engine needs to run at all, but I'm guessing there's a good engineering reason.
I can totally verify that it just doesn’t like extremely cold weather. It wants that ICE running because the battery alone just won’t cut it at those low temps and your oil and fuel need to circulate. Hybrid mode is still utilizing battery power though, you can see it on the hybrid page. I live in Alberta. Freezing temps of -30 Celsius here lots in winter. I drive very short distance to work every day. I was stuck in FORM since I purchased 4xe this winter. Warmer out today, +1 Celsius, took it on a 60km highway trip today in hybrid whole way and after parking for a bit and plugging in at the mall I came out and it fired right up in full electric and no more FORM issue. You just gotta give it a good drive once in awhile and not expect it to be a full electric vehicle when it’s sub arctic outside. That’s why it has a gas engine so you can use it like a regular vehicle no matter what the weather 😊
 

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Yep, just drove about 27 miles, single digits for temps, used mostly gas but some electric. Mostly on inside accessories being on.
Im ok with it, but I don’t drive much so it won’t be that expensive. If I was commuting every day it would run through more gas than we all expected when we bought these. Maybe they will come up with a solution to this.
On hybrid mode it still gets better mileage than a straight gas wrangler, so it’s still saving.
 

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This is what Dan Fry posted on Facebook. This aligns with my own personal experience.

Cold Weather Operation of the Wrangler 4xe

Remote start and regular button start will both work, with an EVSE plugged in. That’s a great way to warm the battery and the cabin using energy from the wall. The Jeep will not shift out of Park until you remove the charge handle, to prevent accidentally driving off while plugged in. The plug icon in the cluster gives you a heads up.

You might see Fuel/Oil Refresh more frequently in cold weather. That’s because short engine runtimes in cold temperatures are most conducive to fuel dilution into the engine oil. If this happens, the solution is to get the engine warm and keep it running for up to an hour and a half to evaporate the fuel out of the oil… or change the engine oil.

Here’s what to expect as mornings get colder. All of this logic is true, whether an EVSE is plugged in or not:

Above ~32°F, and with sufficient battery and fuel, the vehicle will usually power up silently (ICE not running). The exception is if you have a very high HVAC demand.

Below 32°F but above 10°F, the ICE engine will also run at startup. You can select Electric mode to shut it off, relying instead on the electric heaters. There will be a range penalty. If you use remote start in a cold garage, take note exhaust will be emitted.

Below 10°F, the engine will always run until various systems are up to operating temperature. Electric mode will be unavailable during warmup. At these temperatures, the electric heater really isn’t an efficient way to heat the cabin, and your EV range would be greatly reduced by that anyway. The same is true of BEV’s, but they don’t have an ICE to help.

If it’s below ~5°F outside when you shut down, the instrument cluster will advise you to plug in an EVSE to maintain battery temperature. This is only strictly necessary in case the battery temp falls below -20°F overnight. Level 1 or Level 2 are suitable.

All the way down to -20°F, the Jeep can start unassisted (without an EVSE connected). This is the same capability as other Wranglers and most ICE vehicles.

If outside temperature is likely to fall below -20°F, you definitely want to connect an EVSE overnight. The Jeep will wake up periodically and warm and circulate coolant to facilitate a restart. It’s not necessary to also connect a block heater.

With an EVSE connected, the Jeep can start as low as -40°F. This is the same performance a other Wranglers and the best production ICE vehicles - they require block heaters in these temperatures.

Happy Snow-Jeeping! 🙂
Makes perfect sense and seems to align exactly with my experiences. I also think the FORM message pops up anytime electric mode is unavailable. It’s kind of just the default message for hey you’re not using electric today. Lol. Because I can have the FORM message when it’s crazy cold and when it warms up next day no FORM message and I haven’t done anything to clear it except have a warmer day.
 

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Makes perfect sense and seems to align exactly with my experiences. I also think the FORM message pops up anytime electric mode is unavailable. It’s kind of just the default message for hey you’re not using electric today. Lol. Because I can have the FORM message when it’s crazy cold and when it warms up next day no FORM message and I haven’t done anything to clear it except have a warmer day.
On warmer days you’re probably not triggering the ICE on. Hence you’re not seeing the FORM message. I drove today for awhile at speeds up to 55-60mph before the ICE came on. It was about 30F today.
Anyway, just cause FORM isn’t popping up on you, doesn’t mean it’s been taken care of. Check the messages on the dash.
 

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I have the same behavior here in Iowa over the past few days were the highs are around 0.
It is so weird we just had our Wrangler in the shop for this the last 3 days. The funny thing is, is that our Wrangler ran just fine last winter and always used up the electric first. Had no issues with it whatsoever all winter last year. And now after it's been in for an oil change and another I believe on related reason where the Jeep sometimes would not let us start it, but now all of a sudden it is doing this! So I'm assuming they had some sort of update and now this is what we have to live with. Our garage is 65°, yes I know we live in Iowa and it's been right around freezing, but even when the Jeep leaves the garage it does not let us start in electric anymore. Even at 65° in the garage it automatically starts the engine and it never used to do that. Stupid.
 

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It is so weird we just had our Wrangler in the shop for this the last 3 days. The funny thing is, is that our Wrangler ran just fine last winter and always used up the electric first. Had no issues with it whatsoever all winter last year. And now after it's been in for an oil change and another I believe on related reason where the Jeep sometimes would not let us start it, but now all of a sudden it is doing this! So I'm assuming they had some sort of update and now this is what we have to live with. Our garage is 65°, yes I know we live in Iowa and it's been right around freezing, but even when the Jeep leaves the garage it does not let us start in electric anymore. Even at 65° in the garage it automatically starts the engine and it never used to do that. Stupid.
Get an obd2 reader that'll show the pids and you can confirm for yourself if it's operating normally or if you're having a coolant heater lock out issue.
 

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Just installed the mopar grill cover. Havent driven long distances yet, but the main difference for now is that the jeep thinks its way warmer outside than it is. I keep it in the garage at 60F or so and driving 20 minutes in freezing temps (just around freezing) the car still shows 48F. Oil temp actually went up a few degres.

Was also able to drive all electric for 10 miles in sub freezing temps (15F), park it for 1.5 hours outside, then drive back all electric.
 

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It is so weird we just had our Wrangler in the shop for this the last 3 days. The funny thing is, is that our Wrangler ran just fine last winter and always used up the electric first. Had no issues with it whatsoever all winter last year. And now after it's been in for an oil change and another I believe on related reason where the Jeep sometimes would not let us start it, but now all of a sudden it is doing this! So I'm assuming they had some sort of update and now this is what we have to live with. Our garage is 65°, yes I know we live in Iowa and it's been right around freezing, but even when the Jeep leaves the garage it does not let us start in electric anymore. Even at 65° in the garage it automatically starts the engine and it never used to do that. Stupid.
I am actually experiencing the same thing. I live in Buffalo and only went into CHOC and FORM A few times last winter. Was able to start the vehicle in my garage and warm up the vehicle and battery usually in electric, unless it was really cold and then ICE would kick on. After the initial warm up, I could drive around in <10* weather in electric. This year, it is 45* and ICE immediately starts up, I'm in CHOC for a good 10-15minutes an then I'm able to drive in electric for 10 minutes or so before going back into CHOC. I definitely think they updated the algorithm because the vehicle seems to be operating correctly but definitely different than last year.
 
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