2005 Nissan Pathfinder ODB code P0300

[funkycold1]

I'm new to the forum, My Mom has a 2005 Nissan Pathfinder that has been sitting in the driveway for a few years. We have been able to get it started. In the past the transmission has been replaced and the catalytic converters cleaned.

I started it up a few days ago plugged in the OBD reader and it gave me P0300 & another P0300 with what looked like a small 6 and 9 to the right. I know P0300 is for "Random/Multiple Cylinder Misfire Detected" Not sure what exactly the second one means.

It also told me that 3 monitors are Incomplete the catlyst, evap and 02 snsr. According to my Mom it won't go faster then 20 MPH.

Tomorrow I will be changing out the spark plugs as a start. I was hoping someone could lead me as to where to proceed to next. I read it could be the coil packs or fuel filter as well. I am in no means an expert on cars, at all. Although my Father did leave me with a few basics.

Thank you in advance for any help.

[smj999smj]

The fuel filter is not normally serviced as it is located inside the fuel tank. If the same fuel has been in the tank for a few years, you may have bad fuel. Fuel stabilizer should be installed any time a vehicle is going to sit for a period of time. This would cause misfiring as well. If the fuel isn't stale, check the basics. Spark plugs could be an issue if the vehicle has very high mileage on them or the wrong type is installed. From the factory, it came with NGK platinums that are recommended for replacement at 105,000 mile intervals. Fuel pressure can be tested. Rodents can be an issue on vehicles that sit for long periods of time; check for chewed wires and hoses and/or nests in the air cleaner box.

[funkycold1]

The fuel could definitely me apart of the problem now. These issues started when the car was being driven so I believe there are other issues as well. I will go ahead and get some fuel stabilizer.

How do I test fuel pressure?

I'll take a look at the hoses and wires as well.

[smj999smj]

The fuel stabilizer is not going to do you much good now; it needs to be put in before the vehicle is stored. If you suspect stale gas, you can either drain out the tank (which would mean removing it) or add fresh gas and drive it until the old gas is worked out of the system.