P0440 code need a little help?
11-15-2012 | 07:39 AM
#32
JK Enthusiast
Joined: Aug 2012
Posts: 439
Likes: 0
From: virginia beach, Va
the little sliding sensor inside the white cannister got all salted up when i was puddling through hurricane sandy by the beach and siezed the whole thing up. 11 bucks later i was good to go.
12-13-2012 | 06:23 PM
#33
JK Newbie
Joined: Dec 2010
Posts: 9
Likes: 0
From: Hattiesburg, MS
Sorry so late getting back to you. I haven't noticed any difference with the detector, but the PCV has helped a little with the oil consumption. The old PCV seemed in decent condition, but I replaced it anyway. The old PCV was just sitting on top and not snug! I changed to 5w 30 and it seems to run better! My tailpipe is black and seems as if the oil is getting all the way back there! Any ideas?
04-27-2013 | 02:26 PM
#34
JK Newbie
Joined: Nov 2010
Posts: 84
Likes: 0
From: lake zurich, IL
Sorry I never got back to you on this thread. Last time it endes up being my egr valve. Codes were slightly different. Started getting the gascap code again. Been on for about a month. Both times I went to the dealership. They wanted me to replace the gascap first , with an oem cap. @ 25 $ I had already gone through two aftermarket caps and knew it was not the issue. Did research here and replaced the egr valve myself. All was good till now. With slightly different codes. I went ahead and got the lil white vac sensor (21 $ here but better than a 25 $ cap I know is ok.) And the pcv valve for 14 $. I reset the comp. and so far problem fixed.
07-11-2015 | 05:43 PM
#35
JK Newbie
Joined: Jun 2015
Posts: 3
Likes: 0
From: Hartford, CT
P0440 & Gas Cap
I know the is a reply to an old thread but...just had this problem and there is no easy fix to this one. Bought JK, back in June, w/ CEL on, gas cap replaced, CEL came back next day, along w/ gas cap message. Smoke test done, no leak. Code reappeared as we picked up the car. Trip #3 to dealer, another smoke test, and tank fill tube had a slight leak, tube replaced...picked up car today...frickin code back again tonight! WTF! Three strikes, I'm out! No more Jeep!
03-18-2021 | 04:23 PM
#36
JK Newbie
Joined: Mar 2021
Posts: 1
Likes: 0
From: Portland, Tx
Gas cap
I had the same thing as most complaining about the evap system. Mine first started with a GASCAP message. After a trip to the dealer they reset the error and it returned a couple days later, this time followed by P0440. Well it didn't take long before I got the P0442 and the failure P0455.
So after reading this thread I thought I would first try a smoke test. Guess what? No leak!
Ok I thought about replacing all the evap parts. I started with the cheapest the part the pressure sensor. it is twist locked onto the evap canister about $10. Reset my computer and presto, problem fixed. Been 2000 miles.
The piece I replaced is that little white box.
Attachment 148742
Attachment 148743
However, I wanted to know what the hell went wrong. This is what I discovered and it wasn't easy that little bugger is glued shut and I didn't want to contaminate it with saw dust.
That little box is a sensor. It has a plunger inside with a rubber gasket making a tight seal. Once pressurized it stays in place and sends the signal to the computer that the system is in fact pressurized. I theorize that some of the charcoal dust from the evap canister got through the filter and lightly coated the insides of sensor housing and the rubber seals preventing it from maintaining a tight seal; minimal at first but as it got dirtier it became worse. Charcoal dust although not thick was apparent and prevented a tight seal when I applied a vacuum.
The pressure sensor is a simple device with only one set of contacts in it, no electronics or corrodible components. Mine is now working but I live in Mexico and drive a lot of cobble stone roads which must be vibrating the hell out of that poor evap canister which contains the charcoal. Next time I will take it off (comes off easily) and wash it with water and a little dish soap rinsing it thoroughly with distilled water and drying it completely before reassembling. I think this will fix it just fine.
So after reading this thread I thought I would first try a smoke test. Guess what? No leak!
Ok I thought about replacing all the evap parts. I started with the cheapest the part the pressure sensor. it is twist locked onto the evap canister about $10. Reset my computer and presto, problem fixed. Been 2000 miles.
The piece I replaced is that little white box.
Attachment 148742
Attachment 148743
However, I wanted to know what the hell went wrong. This is what I discovered and it wasn't easy that little bugger is glued shut and I didn't want to contaminate it with saw dust.
That little box is a sensor. It has a plunger inside with a rubber gasket making a tight seal. Once pressurized it stays in place and sends the signal to the computer that the system is in fact pressurized. I theorize that some of the charcoal dust from the evap canister got through the filter and lightly coated the insides of sensor housing and the rubber seals preventing it from maintaining a tight seal; minimal at first but as it got dirtier it became worse. Charcoal dust although not thick was apparent and prevented a tight seal when I applied a vacuum.
The pressure sensor is a simple device with only one set of contacts in it, no electronics or corrodible components. Mine is now working but I live in Mexico and drive a lot of cobble stone roads which must be vibrating the hell out of that poor evap canister which contains the charcoal. Next time I will take it off (comes off easily) and wash it with water and a little dish soap rinsing it thoroughly with distilled water and drying it completely before reassembling. I think this will fix it just fine.
This fixed my 09 JKU Rubicon