2021 Jeep Wrangler Auto Start/Stop Dashboard code

[ma_son]

I
I recently just bought my dream car (2021 Jeep Wrangler Freedom Utility 4WD). I've had it for 6 months, and I got hit with the engine light and the Stop/Start combo. I've been able to fix the engine light. Yet I haven't been able to figure out exactly what the problem or solution to fixing the Stop/Start failure. I have read in other forums and chats that there's a chance the fuse has been blown, or a faulty sensor, or even the auxiliary battery needs to be replaced.
Has anyone personally gone through the same problem with this too, and can share some information/tips to fixing it? Thankyou!

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[There’sOnlyOne]

Chances are it's the main battery. Do a search on forum for all the info you need. Figure out if you have eTorque or the auxiliary battery. Etorque (no alternator) you'll need the main 12v battery. If you have an alternator you'll need to replace the main and auxiliary batteries or do the auxiliary battery delete. Info in forum. Walmart H7. AGM would be my choice. Congrats on the "new" Jeep. 2021 has been known to be a good build year.

 

[Heimkehr]

@ma_son
As yours is a used vehicle, consider replacing both batteries (if applicable), or just the main battery while concurrently isolating the ESS battery. Doing so will create a defined reference point for your maintenance records.

Defeat harnesses are available if you don't want to recurringly press the dashboard button to turn off the ESS function. Note that it will still function even if the ESS battery has been electrically isolated. In that instance, the function will be powered by the main battery.

 

[TheBirdie72]

2021 Freedom edition here, too! Nice!

Annnnnd…. Time to replace both batteries! Good luck!

 

[mishkajb]

I have a '21 JK also, and had the same error code upon start. I replaced the auxiliary battery and that cleared the code. It's something you can do on your own, it took me about 30 minutes. There are several how-to videos to guide you through the simple replacement process. If you don't feel comfortable doing that, take it to a Jeep dealership and pay them to do the replacement. Expect a $300-400 bill from them.

I do recommend you find a video that highlights disconnecting the negative terminal for the aux battery on the fuse box. That isn't mentioned in all of the videos out there.

 

[ma_son]

I have a '21 JK also, and had the same error code upon start. I replaced the auxiliary battery and that cleared the code. It's something you can do on your own, it took me about 30 minutes. There are several how-to videos to guide you through the simple replacement process. If you don't feel comfortable doing that, take it to a Jeep dealership and pay them to do the replacement. Expect a $300-400 bill from them.

I do recommend you find a video that highlights disconnecting the negative terminal for the aux battery on the fuse box. That isn't mentioned in all of the videos out there.

I'm starting with replacing both my upstream and downstream O2 sensors. From there, if that doesn't work, I will be replacing the auxiliary battery. I'm just wanting to single out the problem, at the same time replace some things that are coming up on due. Thanks for the info, I have started looking into disconnecting that battery. It just looks very extensive just to get to the bottom. I may try the method of under my tire yet we'll have to see lol

 

[Heimkehr]

I'm starting with replacing both my upstream and downstream O2 sensors. From there, if that doesn't work, I will be replacing the auxiliary battery. I'm just wanting to single out the problem, at the same time replace some things that are coming up on due. Thanks for the info, I have started looking into disconnecting that battery. It just looks very extensive just to get to the bottom. I may try the method of under my tire yet we'll have to see lol

I replaced an upstream O2 sensor specifically to resolve a recurrent P1128 CEL code. It had nothing to do with the health of the vehicle's batteries. Just an FYI so that you're not incurring expense unnecessarily.

While the ESS battery can be accessed by removing the fuse box (aka PDC), the recommended method is to go through the pax-side wheel well. Faster and safer.

 

[ma_son]

I replaced an upstream O2 sensor specifically to resolve a recurrent P1128 CEL code. It had nothing to do with the health of the vehicle's batteries. Just an FYI so that you're not incurring expense unnecessarily.

While the ESS battery can be accessed by removing the fuse box (aka PDC), the recommended method is to go through the pax-side wheel well. Faster and safer.

Yes that is very helpful. I actually matter of fact have that same P1128 engine light code. It'll shoot on every now and then. We'll see what it looks like when the parts arrive. I just ordered them off mopar, so probably within a week we'll see where it's at.

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