Question

On my 1998 Nissan Pathfinder SE 3.3L, what's the most common to cause a problem P0300?

Answer 1

if there is not intake leak, most common problem is most likely spark plug, or clogged fuel injector 

if you have not replace the spark plugs as a normal maintance you can start there. (use oem NGK spark plugs dont use cheap ones)

 

Possible causes

- Faulty spark plug (s) 

- Faulty ignition coil (s) 

- Clogged or faulty fuel injector (s)

- Intake air leak

- Fuel injectors harness is open or shorted

- Fuel Injectors circuit poor electrical connection

- Ignition coils harness is open or shorted

- Ignition coils circuit poor electrical connection

- Insufficient cylinders compression

- Incorrect fuel pressure