2000 Sentra P1491

[kp boggaram]

Hi all,
I have a 2000 Sentra GXE and i had the P1491 on it from past 4 months.
After this SES error came I 've hard time filling the Gas. It think this is because of not releving the vapours from fuel tank and not maintaining the pressure in fuel tank.

I went to a mechanic and he replaced Vaccum cut valve but after 2 days the SES came again. Then he replaced the EVAP Vent control valve. Even then the SES came. Then he replaced the vaccum cut valve bypass valve.

Can any one tell how exactly diagonise this error. ant help in this regard is greatlt appriciated. Thanks Krishna

[vpnavy]

Originally Posted by kp boggaram

...P1491...how exactly diagonise this error...

Until a Specialist replies...

Jump over to: http://x.nissanhelp.com/forums/Knowledgebase/links/113

Download Service Manual - Engine Control 2000 Nissan Sentra

This section contains Possible Cause, DTC Confirmation Procedure, etc. (10 pages of information on DTC P1605)

Hope this helps...

[scottgriz]

I just fixed the exact same error on my 2000 sentra GXE. It was the Vacuum cut valve bypass valve. According to the service manual you can test each of these valves in the system. There is little to no reason that a tech should need to indiscriminately change parts. I am not a service tech, just a DIY. I used the manuals I found on this site, located the parts in question, removed them and tested them. The Vacuum cut valve is a mechanical check valve that can be easily tested by blowing and sucking on the correct ports while covering others and you can easily determine if it is in need of replacement. In my case, I took out the bypass valve and quickly determined that it was stuck open. I replaced that part ($102 at the dealer), reset the SES light and 3 days later after the drive cycle completed, all codes remained clear.
If you have a mechanic replace a part, tell them you want the old parts. Then you will be able to see for yourself what was wrong with the part. There is no reason they should not give you the old parts. Tell them before dropping it off so they don't give you an excuse afterwards that they were tossed.