"Check Gas Cap" and Several CEL Codes

[Brake_L8]

Trying to figure this out as I've learned the Mopar CPO warranty is for drivetrain only and this ancillary stuff isn't necessarily covered.

2016 Ram 1500 5.7L with 47k miles. I don't drive it much and it's parked in an underground garage most of the time.

About 1500 miles ago, I got a CEL and a "Check Gas Cap" message after fueling up. I, of course, checked the gas cap and ran a few tanks through it to see if that would clear it up. Nothing changed.

I then bought a Mopar replacement gas cap, thinking the seal had gone bad. It took a few drive cycles, but the CEL and Check Cap message did go away. A few drive cycles later, it came back and is still on.

I ran the codes and initially had the following:

Stored DTC:

• P0457
• P0456
• P0463

Pending DTC:

• P0455
• P0456

Permanent DTC:

• P0456

I shut the truck off, turned it to Run, and cleared the codes. Everything went away except "Permanent DTC: P0456."

I understand all of these are related to Evap leaks, except P0463, which is something about fuel level. I have not had any issues with the fuel gauge in the cluster. The truck runs fine/normal.

Where do I start with this? I'm happy to DIY it and have seen indications that the purge value could be the culprit. I can poke my head around under the bed and check connections/hoses leading to the evap canister as well. But, didn't know if there was something else to look for.

 

[burner71]

Purge valve solenoid, takes 5 minutes to replace. Usually on the passenger side of your intake, on mine its below the battery.
Its about 20 bucks at Oreillys

 

[Firetruck41]

FYI, warranty should cover emissions related items. That is not considered ancillary.

 

[Cowdog]

I had the same thing first I did the one on the intake but nope after talking to ram the one on the vapor canister it the problem 8 out of 10 times


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[RedSRT4Me]

I had the same thing first I did the one on the intake but nope after talking to ram the one on the vapor canister it the problem 8 out of 10 times


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I had to do the cap, the purge valve, and the leak detection pump.

Finally got rid of those damn codes.

 

[Brake_L8]

Thanks all. Just ordered the new part and it looks super simple to install. I have some generic code reading software with a Bluetooth OBD II reader on my laptop, but have thought about buying Appcar/DiagFCA if it's worth it. Thinking it'd be helpful to look into more modules with more clarity beyond simple CEL codes...

Anyway, we'll see how this goes once the valve shows up. I got another Mopar part instead of something aftermarket.

 

[James OBrien]

I had the same issue and replaced everything and still had a CEL, finally put a hose clamp on the hose that attaches under the hood because it didn't feel very snug and it went away.

 

[Brake_L8]

I had the same issue and replaced everything and still had a CEL, finally put a hose clamp on the hose that attaches under the hood because it didn't feel very snug and it went away.

Did you replace the hose coming off of the valve? The part I ordered comes with a new hose which may help with fitment. If not, I'll keep the hose clamp idea in mind!

 

[James OBrien]

Nope, just went ahead and clamped it for peace of mind.

 

[Tumbleweed]

Sometimes disconnecting the battery for 20-30 minutes will clear "permanent" codes.

 

[Tach_tech]

ESIM and purge valve are the most common leaks I see. Sometimes the gas cap, also seem cracked fuel pumps as well. It’s best to perform a visual inspection and make sure nothing is damaged or loose. With an evap tester though you’re pretty much just guessing and throwing parts at it.

 

[Brake_L8]

Took the truck on a 1,300 mile round trip roadtrip over the past five or so days. I drove it for a few days pre-trip with the new purge valve, then hit the highway. No CEL the whole time and averaged right at 20 MPG.

Got the CEL to pop back on while staying at our Airbnb, and it was for the same codes related to small evap leak. The dash did not claim "Check Gas Cap" though. I pulled the codes with AlfaOBD and cleared them. The CEL did not come back on the 650 mile trip home, which involved several ignition cycles as we stopped for food and fuel.

Going to keep an eye on things there.

Otherwise, I got a super firm and LOUD downshift from 6 to 5 after running the truck all day long at highway speed in the heat. Transmission temp never got above 192* per the dash. The (8-speed) trans was replaced under warranty and has about 4,500 miles on it. Every downshift is pretty noticeable, as if you're heel-toeing a manual transmission car aggressively into a slow corner. I have a call in to the dealership for that one, it's done the aggressive downshifts since it was installed but never anything hard enough to go *clank*.