yes i have the dreadful p0300 code. Came on today along with p0152. what im wondering is..how these two codes effect one another. would o2 sensor throw a code for a multiple missfire? I kinda have an idea whats going on there but i would really like your input in on this..also i had a p0147 before but went away. i need a new maf soon.

 

The P0300 misfires are causing raw fuel to be pushed through the exhaust system and the O2 sensors will report problems from a too rich fuel mixture. Fix the P0300 and the O2 codes should go away.

 

i have no idea what could have caused it to have a missfire..i changed the plugs about 2-3 months ago. OEM nissan plugs from the dealer. i only have 60k on the car

also scanner read that the o2 sensor had a high voltage. guessin thats shot..

 

Bad coils

 

no code yet for which cylinder is misfiring, so I would wait till it shows up....hows the car driving, is the ses light flashing constantly? Coil IMO too

 

Until you fix the P0300 code, don't worry about the O2 sensor code, it may go away because there is too much un-burned fuel in the exhaust system. If you want something to worry about, worry about your catalytic converter. The catalytic converter is burning all that un-used fuel and will "wear out" the converter prematurely and it will plug up, requiring replacement.

If the ECU doesn't give codes for specific cylinders, you may have to replace all the coils.

 

I have no cats. Obx headers and y pipe, gutted cat n that's it.

 

If you replaced coils recently and now have a code then it is likely the coils. Gotta figure out which one now. How does the car run?

 

ive replaced OEM nissan plugs from the dealership about 3 months ago. coils i never did.
The car runs like **** usually on a cold start. sounds like a tractor then the CEL will blink, and stay steady. after it warms up a little, the idle catches it self and the car runs great.
im frustrated with this man.

 

O I misread sorry. Are you sure you did the plugs right? Maybe it is time to check the coils. Any oil in the cylinders during the plug change? What is year/mileage again?

 

The CEL light blinks when the misfires are occurring. But spark plugs will not cause a CEL. There are at least 3 coils failing, otherwise the ECU would give specific codes.

 

no oil on the plug when i changed em. 2002/68k

 

Wow you are kind of lucky to have no oil in bank 5. Try letting the car idle. While it misfires pull one coil at a time. If there is not change then that coil is bad. You will only be able to pull the front coils while doing this.

 

Also your exhaust should stay still while your car is running, if it shakes back and forth that is usually a sign of a bad coil.

 

Whats the condition of your oil, .ie too low?, old and needs changing? P0300 can also be caused by the oil level getting to low or very dirty and the very narrow passage way in the "Varible Timing Solenoid" getting sludge or other impurities getting blocked up in the passage way.

 

i changed the oil 1500 miles ago. full synthetic.

this is so frustrating!!

 

Do you burn oil? Did you check front plugs by pulling.

 

I had the notorious PO300 code for over 2 years and never figured it out to the end.. It wasn't my coil's, injectors, vacuum leak, faulty valve cover.. None of it. It was a piston ring going bad the whole time which created bad compression with leaded to a random multiple misfire.. This is the worst thing that could happen to a Maxima by far.. I had to replace the engine