Frustrating on/off P-0440 code

[sep1006]

2021 Ram Rebel with 5.7 Hemi, 40k miles.

So a few months ago the check engine light comes on. Had it checked and it threw a P-O440 code, emissions. Talked with a few guys and they said the ESIM is usually the issue causing the warning light. Went ahead and changed it out and the warning light went off. Stayed off for about 6 weeks.

Came back on again about 3 weeks ago, the next thing I was told to change was the Purge Solenoid valve. Pretty easy and cheap so went ahead and changed it. Light stayed on for about 4 days then all of a sudden went off again.

Stayed off for a couple of weeks and now the darn thing is on again. Just to be sure had the code checked again, yep P-0440 AGAIN.

Anyone ever went through this or have any suggestions. So darn frustrating!!!!!!

 

[BowDown]

For a durango but it may be your issue as well

 

[Cbty2050]

FTP, because we like guessing and not diagnosing the actual fault.

 

[sep1006]

For a durango but it may be your issue as well

Pretty sure that is the ESIM isn't it? That's the first thing I replaced.

 

[sep1006]

FTP, because we like guessing and not diagnosing the actual fault.

I don't have a smoke system or any other way to test the whole emissions system.

And my main issue is why does the light go off for several weeks, then come back on. Then on/off intermittently. Seems like if something was broke or amiss the light would stay on.

 

[Scram1500]

I had this code intermittently a couple years ago, ignored it and eventually it went away. When this code would happen air would rush into the gas tank when opening the capless flap. My guess something was clogged not allowing the tank to vent properly and somewhere along the line it corrected itself

 

[BowDown]

I don't have a smoke system or any other way to test the whole emissions system.

And my main issue is why does the light go off for several weeks, then come back on. Then on/off intermittently. Seems like if something was broke or amiss the light would stay on.

On my previous truck, I used air (low pressure, maybe 10lbs) and then looked for the hiss. Found cracked/rotted hoses connected to the ESIM and and charcoal canister

I've dealt with that code on my previous truck and it is frustrating, I'd buy a smoke test machine if it happened again

https://www.amazon.com/s?k=Smoke+Machine+Automotive+Leak+Detector

 

[Cbty2050]

This is such a vague code, without being able to monitor data to see if ESIM is closing at correct time, it is just throwing parts. Could be Fuel Tank Pressure sensor, bad wiring(PCM doesn't see ESIM closing), restricted lines and so on.

 

[sep1006]

This is such a vague code

EXACTLY !!!!

 

[Cbty2050]

EXACTLY !!!!

It is actually very easy to diag with a scan tool that can run the EVAP leak test. I prefer the test don't guess method.