Engine Check Light - Now also Stop/Start System Warning Light

[custmfxwg]

Just had this happen to my wife on Saturday; start/stop alert, cel, and very rough idle. Sounds like the same issue the op had as the dealer said they replaced the O2 sensor and valve pan gaskets because they were leaking slightly. Should be ready to pick up tomorrow. The dealer is a good 70 miles from the house so we'll see if it's fixed.

The good news is that we have about 30k miles on the jeep and the dealer seemed to know what it was fairly quickly. Time will tell.

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[Mrcake3014]

My brand new Rubicon JLU (delivered August 6) had the Engine Check Light go on at 117 miles.
Drive it home and the light was off when I turned the Jeep on a few hours later.

At 290 miles it came on again.
Took it to the dealer but couldn't make a service appointment as I was having surgery the next day plus time to recover.Finally took it in Sept 11 and they "fixed" it (apparently a software issue).
Picked it up on the 12th and the light was on again. They reset the system and it seemed fine (off).

Wife is driving it today and the light came on again, AND the Stop/Start System Warning Light has come on. The wife also says it's nor accelerating as smoothly now an there's a slight "tremble" when the engine is running, not smooth like before.

Anybody have any experience with anything like this.Obviously I'm taking it in again, but this is a brand new Jeep and disappointed is an understatement,

I had a problem with the start stop. First they changed the hood sensor. That wasn’t it they had to replace the wiring for the whole system. 2019 with 3000 miles. I was hot!
Also get in touch with Jeep waves. I found them to be very helpful with dealing with the dealership.

 

[custmfxwg]

Just had this happen to my wife on Saturday; start/stop alert, cel, and very rough idle. Sounds like the same issue the op had as the dealer said they replaced the O2 sensor and valve pan gaskets because they were leaking slightly. Should be ready to pick up tomorrow. The dealer is a good 70 miles from the house so we'll see if it's fixed.

The good news is that we have about 30k miles on the jeep and the dealer seemed to know what it was fairly quickly. Time will tell.

So I confirmed today that I had the same issue (or very similar) as @Lustmord. Right valve cover found to be leaking on the O2 sensor. Threw codes P2096 and P0171. New O2 sensor and new valve pan cover gaskets and so far so good.

 

[JeepCares]

So I confirmed today that I had the same issue (or very similar) as @Lustmord. Right valve cover found to be leaking on the O2 sensor. Threw codes P2096 and P0171. New O2 sensor and new valve pan cover gaskets and so far so good.

Hi custmfxwg,
We are happy to hear that your dealer was able to resolve your concerns for you! In the future, please feel free to send us a private message with any questions you may have. We are happy to help!

Kathryn
JeepCares

 

[Dadawada]

Reviving an old post...

At 3 years ownership and 37k miles I just got the same exact symptoms you all are experiencing. Luckily I sprung for the Mopar/Jeep Extended Warranty so I at least have that going for me. My symptoms are slightly different but the dealer read the codes today and they were the same...oxygen sensor, misfire code, etc.
CEL came on, then Autostart not ready, then running rough, CEL flashing (which is bad). Can't get into the dealer until the 25th, over a week away...

 

[mwilk012]

Reviving an old post...

At 3 years ownership and 37k miles I just got the same exact symptoms you all are experiencing. Luckily I sprung for the Mopar/Jeep Extended Warranty so I at least have that going for me. My symptoms are slightly different but the dealer read the codes today and they were the same...oxygen sensor, misfire code, etc.
CEL came on, then Autostart not ready, then running rough, CEL flashing (which is bad). Can't get into the dealer until the 25th, over a week away...

Go somewhere else. Don't drive it like that.

 

[viper88]

I saw one 3.6. How about the rest? Which engines and eTorque or ESS?

 

[Dadawada]

Earlier in the post someone mentioned their problem was an oil leak from the valve cover leaking on the O2 sensor causing it to fail. According to dealer that is exactly what was happening to mine. Thanks for posting that.

Hopefully the parts will not be too backordered and I will get the Jeep back this week.

 

[AEDRUBI]

I have another posting on this…but for clarification, are they saying the oil leak, with oil leaking onto the O2 sensor is the cause of the rough idle, and ESS Warning as well?

 

[Woodynj]

my jeep had the same CEL codes, and was just diagnosed with the a bad O2 sensor and leaky valve cover. I am picking jeep up today, glad it was nothing to hard to find.

Curious if anyone else that had this issue, had vibration at almost all speeds that felt more like out of balance tires? It was not my tires as they we rotated and balanced 3 times with no change. I am hoping what i was feeling was more of a rough engine vibration.

 

[Grizzly64]

My brand new Rubicon JLU (delivered August 6) had the Engine Check Light go on at 117 miles.
Drive it home and the light was off when I turned the Jeep on a few hours later.

At 290 miles it came on again.
Took it to the dealer but couldn't make a service appointment as I was having surgery the next day plus time to recover.Finally took it in Sept 11 and they "fixed" it (apparently a software issue).
Picked it up on the 12th and the light was on again. They reset the system and it seemed fine (off).

Wife is driving it today and the light came on again, AND the Stop/Start System Warning Light has come on. The wife also says it's nor accelerating as smoothly now an there's a slight "tremble" when the engine is running, not smooth like before.

Anybody have any experience with anything like this.Obviously I'm taking it in again, but this is a brand new Jeep and disappointed is an understatement,

Absolutely experiencing this exact issue on my 2020 Wrangler sahara 3.6 Pentastar.

I’m at a loss to fixing this!! Help!

 

[mwilk012]

Absolutely experiencing this exact issue on my 2020 Wrangler sahara 3.6 Pentastar.

I’m at a loss to fixing this!! Help!

First of all, you dug up a years old thread for nothing.

The ESS fault light will come on with the CEL every time. It isn't something to worry about.

If you don't have the technical ability to at least read the fault codes and do some bare minimum testing, all you really need to be doing is calling your mechanic.

 

[Grizzly64]

First of all, you dug up a years old thread for nothing.

The ESS fault light will come on with the CEL every time. It isn't something to worry about.

If you don't have the technical ability to at least read the fault codes and do some bare minimum testing, all you really need to be doing is calling your mechanic.

How is me reading an older thread relevant when my current issue is exactly what’s on the old thread?

 

[mwilk012]

How is me reading an older thread relevant when my current issue is exactly what’s on the old thread?

"The light came on"

That is every single possible fault.

 

[rwaldrop13]

I have a 2018 Wrangler JL Sport Unlimited. I bought it used in June 2025 and the selling dealership had it for a month solving this same issue. Then in January 2026 the issue recurred, and a local shop diagnosed it as a software issue which they thought they resolved. Almost exactly 6 months later the issue has recurred, marking the 3rd time in 12 months this has happened. I plugged in an OBDII reader and get the same error code as before, "Bank 1 Lean". It's killed my MPG, and the jeep is running extremely rough. Bank 1 and 2 fuel trim readings are wildly different. Suggestions? Local shop pointed at Chrysler ECU software issues.

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