Been busting my a** the past few days trying to fix a p0300 code on a 2002 maxima. Read a lot of posts on here with no solution. Tried alot of things. The car would run fine for a day or two then the p0300 will pop up with a rough idle.

The solution in my case was a bad (sluggish) fuel pump. A tip for anyone out there struggling with this code.

 

Wow...how did you discover this ? ? ?

 

would love more info

 

I have dealt with this pesky code before,changed everything,checked for leaks bla bla bla etc,turned out to be a dying maf sensor,was clean as a whistle too,no codes for it or anything,swapped a friends maf and P0300 code never showed again,give this a try first if you don't want to start wasting money on other parts.Check to see if you have a generic maf,Oem is the way to go.

 

Yes, the p0300 is often a "ghost" code. The FSM (for my 2k) lists the following possible causes:

• Improper spark plug
• Insufficient compression
• Incorrect fuel pressure
• EGR volume control valve
• The injector circuit is open or shorted
• Injectors
• Intake air leak
• The ignition secondary circuit is open or shorted
• Lack of fuel
• Drive plate or flywheel
• Front heated oxygen sensor

Quite a wide range of possibilities.

 

Check inside your spark plug tube, might have dropped something in there and not realized.....I had A coil boot fall off once and get stuck in cylinder three and drove with new coil on top of that plug and boot, car ran but threw ur same code so I knew it had to be in that cylinder whatever was wrong after changing A bad #3 coil. Problem was gone after I removed it with needle nose pliers, it was the bottom rubber piece of the boot.

 

I discovered this by trying everything except the fuel pump!!

I tried engine coils, spark plugs, checking for vacumm leaks.. ECU, of course the MAF..LOL..., heated oxygen sensor etc...No Luck

Then it dawned on me, the list of things that can cause the p0300 has "incorrect fuel pressure" and "lack of fuel"..which led me to change the fuel pump and that got rid of the code. Also, my car would misfire and sometimes shut off, which further led me to believe it was the fuel pump.