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Jake, Nissan Technician
Category: Nissan
Satisfied Customers: 3843
Experience:  Experienced collision repair technician, Pulaski Tech graduate and DSM hobbyist.
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Have a 2005 Nissan pathfinder that's throwing p0300 code and

Customer Question

Have a 2005 Nissan pathfinder that's throwing p0300 code and I have changed plugs boots and coil packs, I am broke down 600 miles from home and short on cash. Need help figuring out
Submitted: 1 year ago.
Category: Nissan
Expert:  camerontech replied 1 year ago.

Hi there,

Im cam.

do you have a scanner to view your fuel trims?

I thinking mass airflow sensor issue.

I dont know how its running? but you can unplug to maf sensor and it should still run better if the maf is faulty

Customer: replied 1 year ago.
Don't have a fuel pressure gauge, but kinda leaning towards fuel pump, any ideas on how to check without gauge
Expert:  camerontech replied 1 year ago.

unfortunatly no, not acuratley anyways. if there is a valve on the fuel rail you can press it to see if there is fuel there.

kind of a last resort too, you can give the fuel tank a smack with your fist. IF the fuel pump was stuck, this can get it working again, but it will do it again if the pump is weak.

THe biggest info you will need is does it have 1.spark 2.fuel 3. injector pulse

Customer: replied 1 year ago.
I think itis catalytic converters stopped up now, tried everything else
Expert:  camerontech replied 1 year ago.

can you explain exactly what its doing for me ?


Customer: replied 1 year ago.
When you try to give it has it backfires and I can't get over 40mph, it idles fin with just a slight miss, but won't take any throttle, I checked fuel pressure and it's OK. I unbolted cat's and drove and it ran fine just loud, how can cats stop up all of a sudden?
Customer: replied 1 year ago.
how come 4 cat's on it
Expert:  camerontech replied 1 year ago.

first ,

they put 4 cats on it for emission regulations. it was probably failing standards, so they just add more.

as for the cats doing it all of a sudden, it shouldnt.... thats the funny part. cats plug over time or at least in a couple weeks witha bad running engine.

did you unplug the mass airflow sensor? sand see if tehre was a change?

Customer: replied 1 year ago.
unplugged mass airflow and no change, it ran fine until I got fuel last stop them started running like it is now
Expert:  camerontech replied 1 year ago.

sorry i couldnt help you more.

im going to opt out and another tech sould be able to help you out a little better


Customer: replied 1 year ago.
Expert:  Jake replied 1 year ago.

New tech here.

Lets not over complicate this issue.

If you started having a misfire after your last fill up, then you almost certainly got bad gas.

The easy way to check this is too open the fuel feed line and crank the engine and pump fuel into like a large clear mason jar. If you let it sit and the fuel stays a perfect consistant yellow than it's likely normal, but in your case you will probably notice sediment or seperation from the water and fuel.