Check Engine Light - 19 JLU 3.6 AT

[StewartWrangler19]

Hi all, I apologize if this is the incorrect thread. I mostly lurk but don't interact much!

This weekend my 2019 Unlimited Sahara died on me. Had to jump it and drive 3 hours home (I was out of town, conveniently). Had no issues on the drive home, but it was running the whole time. Jeep was reading 14.1 volts, without fault, the entire way home. Didn't budge at all. After getting home I let it sit for a bit and tried to start it again, but no dice. Replaced the battery. Got 12.9v at idle and hitting 12.5v-high 13s while driving, but never getting to 14v. Fast forward to this morning, my wife calls me on the way to work said the jeep "false started" and there is now a check engine light on. Had to try to start it twice before firing up for her. Drove fine after that but she said its staying below 13v.

Could this be the aux battery causing issues, or is the CEL completely unrelated? When replacing the battery a few days ago I just did the main. Now I'm reading I should have done both at once.

Going to scan it when she gets home from work tonight but figured I'd turn here in the meantime.

Sponsored

 

[jludave]

Could this be the aux battery causing issues, or is the CEL completely unrelated? When replacing the battery a few days ago I just did the main. Now I'm reading I should have done both at once.

Always replace both. When one goes, the other is not far behind.

 

[rohdawg]

Replace that aux battery and your problems will most likely disappear.
Pain in the neck, but like @jludave said, you need to replace both.

 

[unsavory]

The JL always charges in the 12s to low 13s on a fresh battery.

The so called "smart charger" only ramps up to 14V when you're coasting, or if the battery actually needs charging. The voltages you are seeing could easily be a result of a fully charged battery.

 

[mwilk012]

The other battery is the problem, probably was the whole time.

If it has an evap leak code, it needs a software update.

 

[StewartWrangler19]

Well- it was the battery. Replaced the aux after work yesterday and the code cleared itself! Thanks for the feedback. I do still have the service stop/start system light on. But, thats been on essentially since I bought the jeep a few years ago.

 

[mwilk012]

Well- it was the battery. Replaced the aux after work yesterday and the code cleared itself! Thanks for the feedback. I do still have the service stop/start system light on. But, thats been on essentially since I bought the jeep a few years ago.

That’s not acceptable.

 

[Old Dogger]

It’s just best, to replace them both at the same time. With all of the electronics of today on the these Wranglers, they really rely on good batteries. The Factory installed batteries are marginal at best. Just replace with quality AGM Batteries.

Sponsored