# '99 Pathfinder P0300 OBD code



## jdching (Oct 18, 2011)

Hi, newbie here. My pathfinder was working fine until I had the valve cover gasket replaced. 

First day the engine felt like shaking when I stop or on idle and after 2 days engine light went on and the code showed P0325 knock sensor. I relocated the knock sensor but the shaking was still there. 

Next day engine light went on again this time code was P0300 multiple cylinder misfire. I checked all wires and changed spark plugs. Engine light still on.

Anyone got any experience on this? My mechanic said it could be the O2 sensor and I asked another mechanic and he said it could be the coils.

Thanks


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## smj999smj (Jan 1, 2006)

If it's a 99, then you have the VG33E engine, so, you only have one coil, unlike the later VQ engines which had 6 coils and were prone to failure. If it happened immediately upon replacement of the valve cover gasket (you fail to mention which one), I would first check the EGI harness grounds located on the intake upper plenum. If you look at the EGI harness as it runs along the upper plenum, you'll see two sets of ground leads going to two, 10mm head bolts. If they were disturbed during the repair, they may be getting a poor contact. On their own, they were problematic and caused O2 sensor trouble codes to set. A TSB describes a subharness available to run from those ground points to the side of the right bank cylinder head (the harness is easily made and much cheaper than the $80 that Nissan wants). So, try cleaning up the harness eyelets and the mating service of the plenum where they contact. If the upper plenum was removed, check for vacuum leaks at the plenum gasket and check for disconnect vacuum hoses. Obviously, it could be any of a number of problems, but these are two easy checks you can do. Viewing ECM datastream with a scantool would be helpful.


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## Breemania (Feb 14, 2010)

:waving:I am having a similiar problem does anyone have a close up shot of the drivers side vacuum lines toward the firewall for a 1997 pathfinder. I need an inspection and these codes have beed a nightmare! I did the valve cover gasket and the truck runs better than new. I also replaced the 2 lower 02 sensors. Thanks everyone for any help.
Sincerely,

Breemania!


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