hi,
i recently notice there was a check fuel cap light came in my 05 honda odyssey touring. i did reclose the fuel *** and tighten it . but after that the light didn't go. so after one day, the (check fuel light) went. but the malfunction indicator lamp light stayed.

so please tell me what to do.
thanks....

( it been 5 days and the malfunction light still didn't go)
please tell me what to do..
thanks//

 

In order to be of help, the good folks here will need the code that the van has thrown. If you have a code scanner, you can retreive it, or most auto parts stores will retrive the code for you for free.

 

the newer models like the 05 and up Odessey monitors the EVAP system and will set the cel if it sees a problem or if something is just a little off from the factory set parameters. most likely you set a p0456 or p0457 code, which is (p0456) EVAP small leak detected or (p0457) EVAP large leak detected. it is in fact caused by leaving the fuel cap off during or after refueling, which is usually set b/c the fuel tank pressure sensor voltage dropped and caused the system to start monitoring. easy thing to do is either go by the dealer, most are nice enough to do a simple EVAP leak test which only takes about 5 mins, or you can simply disconnect the negative battery cable for about 10-15 mins and then put it back on. make sure you have your radio security code and (if you have navi) your navi code also.

 

did you fill up recently before that! if so just removed the fuel cap and tighten it at least 3 click..and just wait for a couple days and it won't be their. but it depends how you used it though..if you drive it everyday for an hour or more one might might be enought. ...let me know if this help....Joe

 

it will take quite a few drive cycles to clear the "check fuel cap" light, but the cel will not go off for a week or two, depending on the code that is stored in it. and if he only drives it an hour a day or 10 hours a day doesn't mean alot. the system only understands drive cycles which starts when you crank the vehicle and ends when you shut it off. that's ONE drive cycle. if he does that several times a day, it could, theoretically, go off in a few days, but at the end of his post, he stated that it had been a few days and it had not gone off...

 

the check fuel cap message will go away, but the MIL will still be illuminated, until it is cleared with a obd2 scanner. the code will be evap system small leak, nothing to worry about at all.

 

But his MIL is NOT on. Just the fuel cap warning. It coded on the "first trip" moniter. If the ECU runs the evap moniter test on the "2nd trip" and it fails, the MIL will come on and stay on. If the ECU runs the evap moniter test on the "2nd trip" and it passes, The ECU will remove the fuel cap message from the display. But it may take a few days before the ECU runs the test again. Certain enable criteria have to be met.

 

huh? the EVAP system is a constant monitoring system and it monitors the entire time the vehicle is running.
how do you think it knows there is a problem when there is one?

 

umm, his MIL is on. he even said it was on and that the "check cap" light went off...

 

Bull. The ECU runs the test once every drive cycle. But the driving conditions have meet enable criteria before the ECU actually runs the evap test. If the driving conditions arent met during any particular drive cycle, the ECU will wait until the next drive cycle. The ECU does continuously moniter components in the entire PGM system ( which will result in other DTCs) but it does not continously run the evap test. In this particular case, the test failed on the 2nd trip and turned on the mil. P1456 and P1457 are two-trip codes

 

if you would go back and READ my post, I never said it constantly runs the EVAP test, I just said it was constantly monitoring the EVAP system, and it does it more than once per drive cycle. how do I know this??? because I am a HONDA TECHNICIAN and I do this for a living.
now you are correct that certain enable criteria has to be present for the system to monitor b/c we would not want it monitoring on warm up. otherwise, it is constantly monitoring the various sensors for anything outside their operating range. basically, almost everything is centered around the FTP sensor, but there are others that play an important role also, like the primary O2 sensors, MAP sensor, etc, etc...but the main one is the FTP. the PCM constantly watches the FTP sensor for a significant drop in tank pressure, then it checks the purge sol, cannister shut valve, etc, etc, and then if there is a problem, the MIL is set and code is stored.