A week after main battery change-CEL came on.

[ShelbyDee]

Hey experts! So, here's the series of events. My aux battery light came on a few weeks ago. I knew about the dreaded day because I'm on a few Jeep forums, and there's at least a post every single day bout the "avengers" light. Per the advice of multiple users, I followed directions to bypass the Aux battery. Everything was working well, until about a week later, after work I came out to a dead truck. Stock battery was a little over 3 years old, and with the Aux bat going out, I figured it as on it's way out.

So, I changed out the main battery, and all was well. I've kept the aux battery bypassed. Truck has been operating as usual, until yesterday, I started up the truck in the morning and immediately got a solid check engine light.

I went to an auto zone after work to get the code read. They also checked my new battery and alternator, and said they were both "perfect". Truck wasn't acting abnormal or anything.

I then came home and hooked the truck up to Jscan to see if the codes match and if the advanced scan showed anything else, and it did. So that's why I'm here. Do you have any advice on how to proceed? I can't stand the stealerships. They charge you hundreds of dollars just to pull your truck in the bay, they NEVER have loaners, but keep your truck for weeks...I just hate them truthfully so I'm trying to avoid them. I'm out of the 3 year warranty anyway. Any advice will be much appreciated

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[Lost1wing]

With a single battery and colder temps, it is a possibility that the battery voltage dropped low enough to lose communication with computers. I would have expected other battery related faults. Did you clear the codes and see if they come back?

Did you reset the IBS after bypassing the the aux?

 

[ShelbyDee]

With a single battery and colder temps, it is a possibility that the battery voltage dropped low enough to lose communication with computers. I would have expected other battery related faults. Did you clear the codes and see if they come back?

Did you reset the IBS after bypassing the the aux?

I haven't cleared the codes yet. I was wanting to weigh in and see what some of you thought here. And no, after I bypassed the aux I didn't reset anything. I'm assuming when I changed out the main battery, things should have reset, right? I don't have a lot of knowledge on this stuff.

 

[KQL]

I’d double check the clamps on the new battery posts are tight. Heard some have slightly smaller posts, causing a loose connection.

 

[Charles 236]

The P0456 DTC indicates a small EVAP leak detected. The battery doesn't cause this DTC, it results from the evaporative emissions system self test. On some 3.6 Pentastar engines, the purge solenoid hose cracks near the connector, which causes a leak resulting in the P0456 DTC.

The "U____" DTCs are communication loss DTCs that generally do not result in a MIL (check engine) light. They could result from a connection problem, voltage (battery/charging system) issues, problems in modules, wiring modifications.

 

[ShelbyDee]

The P0456 DTC indicates a small EVAP leak detected. The battery doesn't cause this DTC, it results from the evaporative emissions system self test. On some 3.6 Pentastar engines, the purge solenoid hose cracks near the connector, which causes a leak resulting in the P0456 DTC.

The "U____" DTCs are communication loss DTCs that generally do not result in a MIL (check engine) light. They could result from a connection problem, voltage (battery/charging system) issues, problems in modules, wiring modifications.

Is this something that will force me into the dealer? I'm outside of the 3 year warranty. Do you think a Jeep shop could fix something like that?

 

[MRPRmojave]

I just had this same problem this past Sunday, Changed all batteries and worked fine all day Saturday, then BOOM all the lights came on. Took it too dealer Sunday night and told them I changed all the batteries and cleared codes with tazer and no luck........ The dealer hooked up their computer and "wiped" the codes completely out, got it back Tuesday and haven't had a problem. My truck was throwing tranny codes, ESC codes, all kinds of stuff.

 

[Charles 236]

Is this something that will force me into the dealer? I'm outside of the 3 year warranty. Do you think a Jeep shop could fix something like that?

If you don't see an obvious leak point on the EVAP system, you will need special equipment to diagnose it. Cold weather always brings out these issues with the EVAP system, seals harden and leak, hoses crack, etc.

 

[tysongladiator]

I’d double check the clamps on the new battery posts are tight. Heard some have slightly smaller posts, causing a loose connection.

This!!! I literally posted a video on my Youtube channel from about four years ago for this. My negative post was as tight as I could get it but I still had an issue. Then while checking connections, I pulled the terminal completely off. I went to the dealership. They took a terminal from another jeep and I had the same issue. I finally went to the auto parts store, bought a shim, and problem solved. And I've had to keep a shim in it since I've owned it.

 

[tysongladiator]

As @KQL mentioned, I would start with the easiest troubleshooting method and check all connections. Don't just visually check them, give them a little pull to confirm. You'd be surprised at what you find. That was my issue. I have a video on my YT channel from about 4yrs ago on what I found.

Not saying this is your problem, but it's easy to check and you never know. I found mine by chance. If you want to see the video, let me know. I'll go back into my youtube history and get the link.

 

[Lost1wing]

Like Charles236 said, you likely have 2 issues. I would be more concerned with the Evap faults. Gas cap, purge valve like was mentioned are good guesses. You can go to any ma and pay shop if the have a smoker, to find the leak. It is not a Jeep specific issue. You wrote the codes down so go ahead and clear them. The perm code will go away when the issue is fixed. You may also see the pending code still there. The U codes and any other stored codes should clear. Messing around with your battery connections could have induced the U codes.

 

[ShelbyDee]

As @KQL mentioned, I would start with the easiest troubleshooting method and check all connections. Don't just visually check them, give them a little pull to confirm. You'd be surprised at what you find. That was my issue. I have a video on my YT channel from about 4yrs ago on what I found.

Not saying this is your problem, but it's easy to check and you never know. I found mine by chance. If you want to see the video, let me know. I'll go back into my youtube history and get the link.

Yeah, that would be great if you can link it. Thanks!

 

[tysongladiator]

Yeah, that would be great if you can link it. Thanks!

Here's the link:

Please FF past all of my talking to the 5:30 mark where I found the issue. And at 8:20 is where I applied the $3.00 fix. Lol

Note: My dash lights would go crazy and it was throwing all kinds of codes before I fixed this. Again, not saying this is your issue, but your symptoms are similar to what mine was. And.... this also made me regularly start checking other connections. I Offroad a lot so I also regularly check nuts/bolts and hoses as well. I have another video where I found a broken radiator hose that couldn't turned out bad.

Hope this helps!

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