Engine Check Light, Code P0440, and Clearing/Fixing

This is just an informational post that may hopefully help other users more easily than it did me. In Oregon law dictates we're too stupid to pump our own gas. I do admit at times, it's awfully nice to have someone else do it, as I sit lazily on my bum in my nice warm sexy Durango.

But - the 16 year old pimply faced punks they hire on average are 4 times less attentive about my vehicle than I'm ever likely to be. As a consequence, they really don't put much effort into there simple little job.

Example. A week ago, they filled up the vehicle and put the gas cap on incorrectly. As a consequence the Check Engine Light came on. I was away on a business trip, and my wife was worried. I couldn't diagnose or fix the issue (not knowing what it was at the time) from 1000 miles away. So she coulnd't drive anywhere for a week, for fear of damaging the vehicle.

I got home and did some reasearch. Eventually after several hours of hunting, I found the following procedure which cleared up the problem.

1) Determine the engine code cause for the Check Engine Light (C.E.L. or CEL)
2) Insert key into ignition of the Durango
3) turn key to "on" posittion without starting the vehicle
4) VERY VERY quickly turn the key off one click, then on, then off, then on; cycling for 3 turns of the key (NOTE: you might have to try this a couple of times to get it just right)
5) leave on, and read the engine diagnostic code(s) that are output in the mileage counter
6) We got Code P0440 (or P 0440 or P-0440) (variations inserted for search engines)
7) A quick search of the web yielded about 3 or 4 usefull details.
8) Diagnostic code P0440 is the Evaporative Emissions Control System Malfunction (failure) of some type. Details of this type of failure and what the Evap System does for you: http://www.carcarecouncil.org/Emission_Control/evap_system.shtml
9) Other web pages indicated it might be as simple as the Gas Cap being seated incorrectly, or not sealing correctly any more
10) I took it off, yes it was seated incorrectly, and reseatted it firmly
11) Now you need to clear the Check Engine Light indicator (it will clear *eventually* over time if this is TRULY the problem - I recommend you clear it now - that way is a deeper problem with the EVAP system exists, it should come on again - giving another clue something else is amiss
12) One suggestion was to take the Negative (black) cable off the battery for 10 to 20 seconds -- I did - for 30 seconds to be sure
13) You *must* turn the Engine on and start the vehicle all the way before the Check Engine Light might clear - if it doesn't try the following:
14) Turn the ignition on 50 times - yes - 50 times - but be careful, every time you cycle the ignition on (without starting the vehicle) you are turning on the Fuel Pump - continuous cycling can theoretically (according to some posts) cause it to heat up and be damaged - so every 10 times stop and let it rest for a full minute to cool down.
15) After 30 times of doing this (3 sets of 10), turn the engine fully on - see if the check engine light goes off) if it doesn't, do the remaining 20 times (2 sets of 10).
16) if it still doesn't go off, you may have a deeper issue that might require attention of the mechanics

Go to the mechanics - DO NOT tell them you know the engine code and possible system that is at fault. Insure you get a quot for FREE - don't pay for a quote. Then when they present their info - you have a check to see if they are telling the truth.

a p0440 is not caused by a loose gas cap. Its is a evap failure, a loose gas cap will cause a p0442, p0455, or p0456

If 0440 is evap failure and not related to the gas cap being an issue, then how can I go about checking what it might be related to?

Many other postings I found made indications that the gas cap could be at fault (all pointed out it may not be the only fault), and the gas cap was indeed loose, barely screwed in at all, basically just hanging there in place...

Thanks in advance for any additional advice...

New to this board and website, but great tips!

Great information regarding the computer reset and "silly" emission problems with the gas cap.

Thanks for posting.

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TunzRadio - thanks, I'm glad you find it usefull. I chose to post it because it took me a couple of hours to pull together all of the info from various disparate sources. If it can help one person save that much time, then it was well worth it! :-)

Hey folks, just want to say "THANKS!" If you take the time that it took you to figure this out, look up the codes, and fix it.... then subtract the 1 minute that it took me to fix mine after reading this... you will arrive at the total time you saved me from messing around with my Durango after I forgot to twist the gas cap on last night. (I think that's the first time I ever did that, but I was extremely tired after work) Thanks again.

Thanks guys, you helped me clear up P0442 & P0445 which comes up as the Evaporative System. Checked gas cap, cleared code, all is well.
2001 Durango SLT Plus, 4.7

I'm having the same problem with P0440 code. What should I check first?

Excellent! So glad to find your thread when searching for the po440 error. The check engine light kept coming on out of the blue. I went to autozone and checked to see what the error meant. I wish I would have read this thread first. It would have saved me a trip because the error will pop up in your odometer :thumbsup:

Anyways I checked the gas cap and then removed the negative from the battery for a few minutes. Turned the car on and the check engine light turned off.

Thank you for your help everyone!

Just a follow up. It was mentioned previously on this page that P0440 is NOT related to the Gas Cap issue. HOWEVER - EVERY SINGLE time it happens, it's immediately after I get a tank of gas. I'll check the gas cap, and sure enough, it's not tightened down.

I DO BELIEVE that it is the gas cap, regardless of the previous postings by a member. The punks at the gas station don't seem to be able to turn the gas cap all the way over to close it properly. I get P0440 EVERY TIME they don't tighten it properly.

There is a specific gas station they do this at, probably 1 out of every 2 or 3 times I get a fill up. I've complained to the manager, and the owner - to no avail. I no longer go there, even though they have good prices, and the most uber-convenient location for me.

Im havin the code come on now.. P0440 and all-time rad fan running.

Hey idiot hundahunta, the code p0440 IS related to the gas cap. Everybody knows that. If they don't, then it takes a little bit of research on the internet. Also, here's a list of possible causes....

A code P0440 could mean one or more of the following has happened:

The gas cap is not installed or working properly
The purge solenoid has failed
The canister is plugged and not working properly

Possible Solutions
With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
Inspect the EVAP system for cuts/holes in tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks

I'm having the same problem with P0440 code. What should I check first?

A code P0440 could mean one or more of the following has happened:

The gas cap is not installed or working properly
The purge solenoid has failed
The canister is plugged and not working properly
Possible Solutions
With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
Inspect the EVAP system for cuts/holes in tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks