CHECK ENGINE light - code P0440

[Yefim]

Well this morning I was driving to work and my "Check Engine" light came on. Last time I filled up gas was 4 days ago so I don't think it is a gas cap. I brought it to Auto Zone to get the code (by the way, they do it for free in case if you didn't know it) and the code came up:

P0440 EVAP Emission Control Malfunction.

I will give dealer a call tomorrow but maybe someone knows what the hell this could be?

Thanks

[Tone]

Sounds like the gas cap or the EVAC Cannister.

[andy454]

Could be one of several different things. Keep in mind that to run this code you must be at a steady cruising throttle. I mean no tip in and tip out of the throttle for several seconds usually at highway speeds. The code is run once every 24hours if it ran and passed the time before. So your cap could have been loose, but you never met the criteria to run it until now. Here is how the code works. At a certain steady throttle and speed, the vent valve is closed and the vacuum control valve is opened. Once the fuel pressure sensor reaches a certain value the control valve is turned off and the pressure is monitored for a leak. Depending on how fast the pressure falls either a small leak or large leak code is set. The next step is to open the vent valve and see if the pressure drops off in a calibrated time. If not a code for the vent valve stuck is set. I don't have a copy of the codes handy, but I think a 440 is a large leak. Don't hold it to me though. Did yo clear the code and drive it for some time? Could just be the cap if you are lucky. Other large leaks, lines, vent valve not seating, canister, vacuum control valve not working.

[Yefim]

Tone an Andy thank you for your input!

I called my dealer's service department this morning and the tech said that it is most likely because the gas cap was not tightened enough or the plastic "strap" that is attached to the gas cap was caught when I was tightening the cap.

Last time I filled up was about 4 days ago and no light came up. He asked me if I had about half of tank left and I had exactly half-tank left when the light came on so he said that the reading is taken by the system at certain intervals and half-tank level is one of them. He suggested to fill up again to full tank, then make sure the cap is well tightened, and then the next time the reading is taken the light should go away. I did that and so far the light was still there while I drove to work. We'll see if it goes away and if it doesn't I'll try disconnecting the battery.

Hopefully I am worrying for nothing. Thanks again everyone!

[SPAZZ]

I had to disconnect my battery for about 1 hour before the check engine light would reset. Then it came back on a month later, related problem was different, too long to explain and probably every one on this post knows the details, so I don't have to tell the story again........

[Yefim]

I had to disconnect my battery for about 1 hour before the check engine light would reset. Then it came back on a month later, related problem was different, too long to explain and probably every one on this post knows the details, so I don't have to tell the story again........

Hey Spazz, it seems that there is no "universal" solution for the P0440 code. Some people fixed it by just disconnecting and reconnecting the battery and it was gone for good. In other cases it was a leaking or loose gas cap, vacuum solenoid, or a vacuum hose. It could be an electrical problem, bad sensor, or bad software (someone mentioned they had a software update done by the dealer), etc... I had an Alldata.com membership and when I punched that trouble code for VX it gave me a bunch of pages and tests that needed to be performed to eliminate all possible causes. Most of them required dealer's diagnostic equipment.

So I think it would be great if you could share what took care of it in your case if you don't mind.

Thanks

[Capri]

did you ever get the engine light to turn off? I got the same code recently, tho the dealership is not willing to look at my car cuz of the SC...bummer

[Tone]

Something like the ScanGauge or Interceptor Scan Gauge I offer can let you monitor parameters while driving which can be very helpful in troubleshooting plus you can read and reset the Check Engine Light.

Since a 440 can easily be caused by incomplete tightening of the gas cap, it is a very common code. Resetting it by pulling the battery does not fix the problem but allows the computer not to have to complete the number of cycles needed to reset it on it's own. An easier way to reset the computer (besides using a gauge) is to remove the black plastic cover below the CD changer area and unplug the 3 colored connectors (stay away from Yellow sheathed wires as always) for a few minutes - this way saves your rado presets and clock settings.

[tomdietrying]

Yeah, my engine light came on today. I have 45,000 miles on my VX and was wondering if it was an automatic "Check Engine Light" that would come on at a certain mileage. This happened to me when I had my Susuki.

Anyhow, I'll check the the gas cap and take it over to Pep Boys and check it out.

Peace.
Tom

[tomdietrying]

Well, after checking my gas cap, it sure seemed like it opened VERY easy. I don't remember it opening up that easily when I fill up. It feels like it is not catching to make it lock tight. I didn't get to look at it very long, is there anything to wear out on the gas cap?

Peace.
Tom

[Capri]

I bought an aftermarket gas cap to replace the factory one, there were some wear and tear so I figured it's worth a shot. I got it tightened to the point where I couldn't twist it back open - had to use a wrench. Though the tightening of the cap probably isn't a possibility now.

Wonder if it's the o2 sensors..

[Solitude]

Ok.. so I have the 440 code.. I have searched the term PO 440, 440, and 440 code.

I found that others have had the problem but no one besides Tone gave a completed fix.. just a little bickering about using the search function..

Search doesnt work real well unless a fix is posted.. (so I said all that to say this)

Has anyone ever thrown 440 and figured out an accurate fix for it?

I am gonna try a new gas cap 1st. since I am on the road and my 16 year old is driving it.

I will try the vacuum line next if I can figure which side is the right side of the engine..

I am also gonna try the dealer when the rest doesn't work since it still should be under the emission warantee..

I will post the 440 fix when I figure it out..

if anyone else has FIxED a 440 code.. please chime in

peace and thank you

Jeff

[Solitude]

Ok..I fixed it. for 7.99 at auto zone and a 3/8 drill to drill a hole for the keeper

it was the gas cap.. I guess I could have bought a new O-ring, but the gas cap fixed the code 440,

just a heads up

Jeff

[Marlin]

I have had mine off and on for the last couple of months, sometimes right at startup, sometimes while driving and so on...
I just reset it with my Scangage, and since this problem seems to be an emissions issue more than anything, I ignored it, and guess what....hasn't been in about2 weeks, and I am well into my second tank since then. So it could be from over filling and I just had to wait for the canister to dry out?

[Gussie2000]

I bought an aftermarket gas cap to replace the factory one, there were some wear and tear so I figured it's worth a shot. I got it tightened to the point where I couldn't twist it back open - had to use a wrench. Though the tightening of the cap probably isn't a possibility now.

Wonder if it's the o2 sensors..

Actually my gas cap had the same issue,when i bought the VX & went to full up the 1rst time i realized that the cap had few missing pieces of the white ring that locks & click three times after you twist the gap.

I replaced it with a 1999 trooper gas cap at strauss auto,the nice feature about this gas cap it comes with a black button that release the vacuum pressure (sometimes not) & had ended up loosing it with a plyers,but it does do the job very well