# '00 Sentra throwing P1491 and P0325



## Thatcrispykid (Sep 4, 2012)

Hi, guys. I have a 2000 Nissan Sentra SE 2.0L with a manual 5-speed transmission and 212,000 miles (!). I'm getting two engine codes: 1491 (vacuum cut valve bypass valve) and 0325 (knock sensor).

From what I understand, the knock sensor doesn't cause a CEL, so I'm wondering if it's bad wiring that's causing the two codes. I know the VCVBV can be replaced or at least blasted clean of loose charcoal.

I need this fixed in the coming weeks for NYS inspection. Thank you!


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## smj999smj (Jan 1, 2006)

If you have charcoal in the VCVBV, then you have a big problem! That would mean the canister inner liner failed and let charcoal into the system, which means it will all have to be blown clear from the canister to the purge valve. I've seen this on R50 Pathfinders, but never heard of it on Sentras. There are a number of things that can cause the P1491 trouble code; without doing the FSM diagnostic procedure for the code, you're only guessing that it actually is the VCVBV. As far as a wiring issue, it shouldn't share the same circuit as the knock sensor. I would concentrate on the P1492 code and get that fixed, erase the codes, the drive the vehicle a few days and recheck for stored codes.


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