# 2000 nissan sentra service engine soon code P1491



## sandrk (Sep 13, 2007)

I have a 2000 nissan sentra with service engine soon code P1491. It comes on at about 140 miles after having it reset and it will go off after about 300 miles seems to be pretty consistent. 
any help?


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## saint0421 (Sep 24, 2006)

from the FSM hope this helps: 

DTC P1491 VACUUM CUT VALVE BYPASS VALVE PFP:17372 
Description UBS000CJ 
COMPONENT DESCRIPTION 
The vacuum cut valve and vacuum cut valve bypass valve are 
installed in parallel on the EVAP purge line between the fuel tank and 
the EVAP canister. 
The vacuum cut valve prevents the intake manifold vacuum from 
being applied to the fuel tank. 
The vacuum cut valve bypass valve is a solenoid type valve and generally 
remains closed. It opens only for on board diagnosis. 
The vacuum cut valve bypass valve responds to signals from the 
ECM. When the ECM sends an ON (ground) signal, the valve is 
opened. The vacuum cut valve is then bypassed to apply intake 
manifold vacuum to the fuel tank.


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