P0300 code after exhaust
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4th Gear
Joined: Jul 2023
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P0300 code after exhaust
Hey guys, I am new to corvettes. I just recently found a 2004 C5 vet with 117000 miles on it for 6800$. It was such a good deal I couldn't refuse. The only thing is is its throwing a p0300 code and sometimes a p0174 code. The guy I bought it from said he took it to a mechanic and the mechanic said it was from the exhaust that was put on the car. The car has been driven with this flash check engine light for a year. Will that exhaust throw those codes? When these codes are thrown will it affect how the car runs? The car doesn't seem to miss a beat performance wise and runs good. The car has a subtle shake when stopped when engine running but this seems like a common thing with these vettes. Let me know what I should do to try to fix the light, or if I should not worry about it because it is caused by the exhaust.
-Thanks
-Thanks
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,214
Likes: 1,173
From: Southlake, TX
This probably has nothing to do with your exhaust.
The P0300 means your computer is detecting a random misfire but not often enough to throw a specific cylinder fault. For example, If you had a specific problem you would get a P0304 meaning the number four cylinder.
I'd start with the simple stuff and check connections with your coils, plug wires and plugs. Also with 117k on the engine, do you have an idea of when the plugs were changed? You would not be the first guy to get a Corvette where the plugs have never been changed.
The P0300 means your computer is detecting a random misfire but not often enough to throw a specific cylinder fault. For example, If you had a specific problem you would get a P0304 meaning the number four cylinder.
I'd start with the simple stuff and check connections with your coils, plug wires and plugs. Also with 117k on the engine, do you have an idea of when the plugs were changed? You would not be the first guy to get a Corvette where the plugs have never been changed.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,435
Likes: 3,982
From: Cape Coral, Florida
Find yourself a diagnostic shop and take it there…not to a dealership or general repair shop because they only change parts…if the check engine light has been flashing if that’s what you mean that is a catalytic converter damaging misfire…one or both cats may be “nuked” so maybe down the road you will see a P0330/P0340…an exhaust wouldn’t cause this…maybe an exhaust leak but not the exhaust itself.
Thread Starter
4th Gear
Joined: Jul 2023
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This probably has nothing to do with your exhaust.
The P0300 means your computer is detecting a random misfire but not often enough to throw a specific cylinder fault. For example, If you had a specific problem you would get a P0304 meaning the number four cylinder.
I'd start with the simple stuff and check connections with your coils, plug wires and plugs. Also with 117k on the engine, do you have an idea of when the plugs were changed? You would not be the first guy to get a Corvette where the plugs have never been changed.
The P0300 means your computer is detecting a random misfire but not often enough to throw a specific cylinder fault. For example, If you had a specific problem you would get a P0304 meaning the number four cylinder.
I'd start with the simple stuff and check connections with your coils, plug wires and plugs. Also with 117k on the engine, do you have an idea of when the plugs were changed? You would not be the first guy to get a Corvette where the plugs have never been changed.
I am going to change the plugs and wires, I figure that wouldn't hurt. Thanks for the Info!
Thread Starter
4th Gear
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I think the exhaust is a catless exhaust. I am going to try changing the plugs. I started it this morning with hood popped and I'm seeing a small vibration in the morning. If that doesn't cause a fix I will definitely take it to a shop.
Drifting
Joined: Mar 2018
Posts: 1,365
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From: New Jersey
You can get a cheap scanner that supports reading the mode 6 data. That will tell you what cylinders are misfiring and the total count of misfires per cylinder. That can pin point if there is a problem in one of the cylinders. It will also tell you how some of the sensor data is like mass airflow, or manifold pressure or fuel trims. Then you can go from there.
Thread Starter
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New Plugs
I put new plugs and plug wires. The car is still throwing a p0300 code. The plugs looked rough and fouled out. I am thinking it is something to do with the computer making the car run lean from the cats. I am going to go get the car tuned. I am worried that because the code has been on the car for about 2 years before I owned it and the car has ran lean that whole time if the car has any long term engine damage because of it.
