multiple codes - headache
Thread Starter
Junior Member
Joined: Jan 2011
Posts: 4
Likes: 0
From: bowling green, ky
multiple codes - headache
So here's the story.... a few weeks ago I got the codes p0301, p0302, and one that said I was running lean. After personally changing the plugs and $500 later, truck ran like new for about 2 weeks. Another check engine light came on. My truck was shaking bad when accelerating when cold. So I went and had the codes checked again. Now I am getting 4 codes... p0300, p0305, p0306, and p0420. I think the first three are back at the plugs, which has me totally confused, and the last code has to do with the cat.
Any advise, direction, or kind word would be greatly appreciated!
Any advise, direction, or kind word would be greatly appreciated!
Senior Member
Joined: Jan 2011
Posts: 192
Likes: 49
Didn't see what motor you have, but you have multiple cylinder misfires. Cat code is a result of unburnt fuel. If left for long, the misfire will ruin the cats.
Spark plug boots are notorious for causing misfires, and would likely get worse after removing and reinstalling them. Vacuum leaks and fuel supply problems will cause the same codes, and poor driveability. Cold running issues are common; often times caused by intake manifold leaks. Check the PCV hose for leakage or collapse.
Check your fuel filter for restrictions, and fuel pressure as well. Modular engines are known for eating coils as well.
Spark plug boots are notorious for causing misfires, and would likely get worse after removing and reinstalling them. Vacuum leaks and fuel supply problems will cause the same codes, and poor driveability. Cold running issues are common; often times caused by intake manifold leaks. Check the PCV hose for leakage or collapse.
Check your fuel filter for restrictions, and fuel pressure as well. Modular engines are known for eating coils as well.
Last edited by sfdude; Feb 9, 2011 at 06:04 PM.
Thread Starter
Junior Member
Joined: Jan 2011
Posts: 4
Likes: 0
From: bowling green, ky
Didn't see what motor you have, but you have multiple cylinder misfires. Cat code is a result of unburnt fuel. If left for long, the misfire will ruin the cats.
Spark plug boots are notorious for causing misfires, and would likely get worse after removing and reinstalling them. Vacuum leaks and fuel supply problems will cause the same codes, and poor driveability. Cold running issues are common; often times caused by intake manifold leaks. Check the PCV hose for leakage or collapse.
Check your fuel filter for restrictions, and fuel pressure as well. Modular engines are known for eating coils as well.
Spark plug boots are notorious for causing misfires, and would likely get worse after removing and reinstalling them. Vacuum leaks and fuel supply problems will cause the same codes, and poor driveability. Cold running issues are common; often times caused by intake manifold leaks. Check the PCV hose for leakage or collapse.
Check your fuel filter for restrictions, and fuel pressure as well. Modular engines are known for eating coils as well.
I have the 5.4. I'll check few things you recommended. I just checked the price of the cats and definitely want to find the problem before I smoke them!