If you live somewhere cold it’s only a matter of time until your Jeep enters FORM and getting it out to go back to normal operation hybrid/electric operation is usually a matter of getting the oil hot enough, 194 degrees and above, for a period of time.
Read more about FORM – 4xe Fuel Oil Refresh Mode – FORM
Getting the Oil Hot Enough
In warmer weather the oil will get hot quickly but in cold weather it’s difficult to get it hot especially quickly. Even a 20 min highway drive in less than 40 degrees is barely enough time to get the oil to 180 degrees. Engine coolant heats and cools much quicker than the oil so fully up to temperature coolant really doesn’t mean warm oil. You will find in cold weather even the coolant will linger in the 195 degree range, even on the highway when in the summer it could be 210-220 degrees easy.
Blocking Air Flow
If you’ve ever seen a large truck or tractor trailer with the grille covered up in cold environments that is done to limit air flow through the radiator allowing the diesel engine to get fully warmed up. This method actually works very well on the 4xe. There’s a few ways…
Mopar JL Winter Cover
Mopar makes a winter cover for the JL that is intended for the diesel equipped JL but actually works quite nicely on the 4xe.
DeFORM or Slot Plates
Another clever method is purchasing or making plates that fit into the grille slots. As of this writing a company in Canada is making plates called DeFORM that cover the bottom 2/3 of the slots to limit air flow. Many people have reported that they are extremely effective plus they can be quickly removed since they just snap into the slots. Find the DeFORM plates on eBay.
Some people have made their own and we gave it a shot using plastic from a storage container. We cut a template piece from cardboard and cut the pieces from the container using a pair of metal shears. Tabs we bent into the pieces by using a heat gun followed by a coat of paint. We only covered the middle 5 slots since the outermost ones seem to provide little airflow and the passenger side outer slot has the inlet to the airbox.
It was a rare 63 degrees in eastern PA and we gave the plates a test. You can see the Jeep’s oil was pretty hot in 10 minutes. Note the Jeep Easter Egg – oil temp shows 419 when the engine hasn’t been run. 419 is the area code of Toledo, OH.
It’s also worth noting that the Jeep didn’t overheat with the plates on even after extended driving. In reading other people that have experimented with covering the grille most agree that the likelihood of the Jeep overheating is low since the cooling system is quite robust. Still any much warmer the plates would get removed.
Below is a pic of extended driving (60 miles) in 31 degree weather. You the oil was nicely warmed and it closely followed the engine temp. Also, on this particular test our 4xe exited FORM.