Will 440 code clear by itself after replacing gas cap?

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  #1  
Old 02-15-14, 10:14 PM
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Will 440 code clear by itself after replacing gas cap?

I got a 440 code on 1998 Nissan Frontier 4WD. Lost gas cap, bought generic one and started getting intermittent 440ís. After putting up with it for a couple of months I went through the trouble of buying an original Nissan gas cap.

Now, my question is: Will the 440 code (and engine light) clear by itself after a while, or do I need to reset it.

If it will eventually clear by itself, when should I expect? I've already driven back and forth to work 2 days, ie. 4x15miles.
 

Last edited by stickshift; 02-16-14 at 02:00 PM. Reason: Corrected 404 to 440
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Old 02-15-14, 10:30 PM
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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.

If the P0440 trouble code was caused by the cap then it should clear in several days.
 
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Old 02-16-14, 07:56 AM
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Code

The OP says the code is 404, not 440.
 
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Old 02-16-14, 08:52 AM
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A P0404 code is an EGR trouble code and has nothing to do with the gas cap.

Thomas.... if you did not make a mistake and you are getting a 0404 code..... then you need to be looking into troubleshooting your EGR valve for a possible stuck condition or not fully closed valve. Your vehicle should be stumbling and running rough. Your gas cap would have no effect on this code.
 
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Old 02-16-14, 09:57 AM
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I'm very sorry. The code is 440. I typed 404 by mistake.
Is there a way to correct it, as not to mislead future searches?
 
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Old 02-16-14, 01:39 PM
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The check engine light just went off today. So it took about 5 drives for me to clear. I guess it also depends on driving pattern how fast it clears?

I did though hook up a code reader and seems like the P440 code is still stored in the truck's computer's memory. I did not clear it. I guess the code stays. Perhaps clears by itself later?
 
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Old 02-16-14, 02:04 PM
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Nope..It will always be stored unless cleared. Thats one thing I've done on cars people asked me to look at for purchase. No light...but a bunch of codes can indicate recent repairs or problems.
 
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Old 02-16-14, 08:07 PM
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Thanks. I cleared it.
Does clearing make the truck's computer rerun the tests next time I drive? My code reader now says that Evap is "not ready".
 
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Old 02-19-14, 12:10 PM
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Well, after driving back and forth to work, the code reader now says that EVAP and EGR are ready, and no new codes have appeared. So all is well.

So it must have run the EVAP and EGR tests successfully. I read in the shop manual that the way to trigger the EVAP test is to drive for at least 17mins and then drive for 3 minutes at a speed of 53-60mph. That is what I did returning from work, but I cannot tell if that was what caused the EVAP test to run (successfully).

So seems to me that explicitly clearing the 440 code set the EVAP and EGR test status as pending, and then driving at the 17 min + 3min # 53-60 mph pattern caused the tests to be run (sucessfully). Iím not sure why clearing the 440 code affects the EGR test status, there must be some connection.

In any case, if you are reading this sometime in the future, take this last post with a grain of salt. Iím out of my depth here, so my statements are just speculation at his point.

The important thing is that the 440 code and engine light caused by the lost gas cap has now cleared and all looks ok.
 
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Old 02-19-14, 12:14 PM
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Excellent work....I think you have a good understanding of how it functions.
 
  #11  
Old 02-19-14, 11:02 PM
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There are certain provisions in the engine computer to set not ready prompts like that. One is so that you can't pull up in front of an inspection station, clear any trouble codes and zip thru inspection. When they do a scan they get that not ready and won't pass you.

Also... with most ECM's...... the codes are erased after X amount of starts. Could be 30-50 if I remember correctly.
 
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