P0300 Need some help

[MoneyTrell]

Hey I have a Aura with about 232k miles. I just get a P0300 and i notice i have a rough idle but it starts up fine and when i am on the highway it keeps up speed fine. Everything seems to be running good. I am wondering do you think it just time for me to change the spark plugs? I am also wondering if it was the spark plugs wouldnt it be a certain cylinder instead of a random? I am also not sure when the plugs been changed because i got the car used.

[billysvue]

SOunds like a great opportunity to change them... and all fluids and filters...

[MoneyTrell]

Fluids have been changed. But it is getting close to do a oil change. I dont think that could be causing it.

But you think if i change the plugs that should fix it?

[fdryer]

If you have your owner's manual, check for maintenance intervals in regards to replacing spark plugs. Most Saturns have platinum plugs good for 100k miles unless an owner's manual specifies less. If no owner's manual, try here; http://www.saturn.com/owners/owner_r...s/manuals.html

[MoneyTrell]

Originally Posted by fdryer

If you have your owner's manual, check for maintenance intervals in regards to replacing spark plugs. Most Saturns have platinum plugs good for 100k miles unless an owner's manual specifies less. If no owner's manual, try here; http://www.saturn.com/owners/owner_r...s/manuals.html

yeah that what i thought. You think it could be my 02 sensor? Because idles rough but runs good. I remember me checking a few plugs a couple of months ago and they where white but not black

[fdryer]

While color is only one factor in determining plug wear, other factors need to be considered such as mileage and type of plug. Normal plugs should show tan coloring. White can be interpreted as lean fuel mixtures unless they're relatively new. New plugs have sharp edges on side electrodes with very little combustion deposits anywhere. Worn plugs will show side and center electrode wear as rounded edges and a larger gap than specified. These descriptions are termed as plug reading, similar to palm reading but based on science from past history of engine running and various plugs. If in doubt, replace spark plugs and stay with recommended stock plugs.

O2 sensors have no real expiration date whether using mileage or time. As an electronic component designed for long life, some fail prematurely while others last the life of an engine so a median life expectancy is recommended. Most O2 sensor replacements are from troubleshooting using error codes and/or hard diagnosis along with symptoms. I cannot tell you to replace O2 sensors without more information. Nothing posted points to an O2 sensor issue.

[billysvue]

Originally Posted by MoneyTrell

But you think if i change the plugs that should fix it?

YOu just bought a used car and don't know jack about it's past maintenance... Plugs are a maintenance item...

[greenman]

this is definitely one of the possibilities for that eng:

http://www.cartruckinfo.com/engine-m...ough-idle.html

[MoneyTrell]

It is a 3.6 so that not the same engine as me. Yeah i didn't know much because it is my Girlfriend car and she bought it from some guy. But he didn't tell us much about it.
I will probably just replace the spark plugs sense that is a regular maintenance item and I know the catalytic converter is going bad but in my county you don't need emissions. But i bypass that but i do not think the Random Misfire is caused from the Catalytic converter.

Because if it was the o2 sensor upstream i should get a DTC for the 02 sensor and not Random Misfire i thought.

It weird because when i turn the DTC off it will stay off for about a day then come back on. And it runs good so i am not sure.

[greenman]

Originally Posted by MoneyTrell

It is a 3.6 so that not the same engine as me.

my bad. i've no idea why i thought it was a 2.4l now.

[MoneyTrell]

It's werid. I notice it only comes on when the car is hot and when I turn the car off and let it sit for awhile and turn it back one it goes off. Car runs good and kind of idles a little rough