Check Engine light with only 400 miles

[TheLodgeOne]

Hey Everyone,

Just wanted to put this out here and see if anyone else has had this experience.

Custom ordered a 2021 JLUR, manual 3.6L, about 2 months ago. Two weeks ago stopped in at the dealer to grab my title and left the Jeep running in the parking lot. Obviously it had warmed up quite a bit, so when I came back and started to drive away, my check engine light came on and the start/stop system failure light.

Luckily I was at the dealer so I had them check it out, but I had planned to go to Big Bend National Park the next morning for 4 days (from KS.. which is about a 14 hour drive). Apparently it threw obscure codes they haven't seen before so they weren't sure what it was. After sitting in their booth, it cooled down and once the codes were cleared, it didn't pop up again, so they told me that maybe it was just a fluke.

Next day, on the highway for about 8 hours south to TX, and hit some traffic and went from highway speeds to some start stop traffic and it was warm outside. Once again, oil temps got up to north of 224 degrees and I had the check engine light and start/stop failure light come on. Once the traffic cleared, I also noticed that with that instance, the car was almost in limp mode. Previously I was in 6th gear going about 70/75 mph. Now the car struggled to get up to 65 mph in 4th and if I shifted to 5th or 6th, it would just lose speed immediately. After pulling into a gas station and letting it cool down for half an hour, the start/stop light went off, the check engine light stayed on and speeds were regular. Over the next 3 days this happened again while in Big Bend off-roading and my oil temps got above 226 degrees F.

When I got back and took it in to the dealer, they once again weren't able to tell what it was. I had them change my oil and rotate my tires while they were at it, but they said they were going to have someone drive it home to see if they could replicate the problem. At which point I said NO THANK YOU, I will drive my own Jeep around and if the problem comes back up, I will bring it in immediately.

So conclusions: No one knows what the issue is. Seems to flare up when the oil/operating temps are high, which leads to a failure in the start/stop system and retards highway speeds? Unless there is a sensor that is turning the start/stop system off because it's thinking the temps are too high? But obviously I know that's not overheating, because those temps are within the norm.

Please let me know if anyone has had any similar experiences.

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[goochman]

My start/stop failure came from the cam phaser/solenoids. Mine kicked the lights off when cold though - after sitting 12+ hours. It took about 2 weeks for the Dealer to diagnose my issue. Hopefully you have better luck.

 

[TheLodgeOne]

My start/stop failure came from the cam phaser/solenoids. Mine kicked the lights off when cold though - after sitting 12+ hours. It took about 2 weeks for the Dealer to diagnose my issue. Hopefully you have better luck.

They had it at the shop for 2 weeks? I can't even imagine.

 

[LABLUE]

What codes set, sounds like they had the express tech scan it.....

 

[TheLodgeOne]

What codes set, sounds like they had the express tech scan it.....

They did at first, then they pulled it into the garage to plug it to the computer and told me that it was throwing obscure codes they haven't seen before. It was kind of on me, as I was rushing for time since I had to leave the next morning, so I didn't ask exactly what codes they were seeing.

I got the issue again over the holidays when I was in CO going up some snowy slopes and getting the engine hot again, but it went away after a day again. It's harder to replicate it now that it's cold out everywhere, so I may just wait until spring and get it to happen and take it in immediately.

 

[JimLee]

Crawl up under your jeep on the passenger side and look up at the catalytic converter, very close to there is a connector for the passenger side 02 sensor. Check the connector for evidence of any oil. There's a few people that have had a valve cover leak on the back of the passenger side head, it drips down and burns off on the cat so usually no drips on the ground, when the engine is not hot enough it runs down and collects at that connector eventually shorting it out and throwing a bunch of codes along with going into limp mode. May not be your problem but worth taking a look at.

 

[itzgigibabyy444]

Hey Everyone,

Just wanted to put this out here and see if anyone else has had this experience.

Custom ordered a 2021 JLUR, manual 3.6L, about 2 months ago. Two weeks ago stopped in at the dealer to grab my title and left the Jeep running in the parking lot. Obviously it had warmed up quite a bit, so when I came back and started to drive away, my check engine light came on and the start/stop system failure light.

Luckily I was at the dealer so I had them check it out, but I had planned to go to Big Bend National Park the next morning for 4 days (from KS.. which is about a 14 hour drive). Apparently it threw obscure codes they haven't seen before so they weren't sure what it was. After sitting in their booth, it cooled down and once the codes were cleared, it didn't pop up again, so they told me that maybe it was just a fluke.

Next day, on the highway for about 8 hours south to TX, and hit some traffic and went from highway speeds to some start stop traffic and it was warm outside. Once again, oil temps got up to north of 224 degrees and I had the check engine light and start/stop failure light come on. Once the traffic cleared, I also noticed that with that instance, the car was almost in limp mode. Previously I was in 6th gear going about 70/75 mph. Now the car struggled to get up to 65 mph in 4th and if I shifted to 5th or 6th, it would just lose speed immediately. After pulling into a gas station and letting it cool down for half an hour, the start/stop light went off, the check engine light stayed on and speeds were regular. Over the next 3 days this happened again while in Big Bend off-roading and my oil temps got above 226 degrees F.

When I got back and took it in to the dealer, they once again weren't able to tell what it was. I had them change my oil and rotate my tires while they were at it, but they said they were going to have someone drive it home to see if they could replicate the problem. At which point I said NO THANK YOU, I will drive my own Jeep around and if the problem comes back up, I will bring it in immediately.

So conclusions: No one knows what the issue is. Seems to flare up when the oil/operating temps are high, which leads to a failure in the start/stop system and retards highway speeds? Unless there is a sensor that is turning the start/stop system off because it's thinking the temps are too high? But obviously I know that's not overheating, because those temps are within the norm.

Please let me know if anyone has had any similar experiences.

did your jeep come with a gas cap? like when you open the cover is there a twist off? My 2021 sahara didnt have one but apparently is supposed to from everyones statements. and thats why my check engine light may be on

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