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Amedee, Kia Technician
Category: Kia
Satisfied Customers: 26605
Experience:  ASE Technician advanced level specialist. Wisconsin certified emissions state inspector
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2006 Kia: check engine light..rough intermittently..runs fine

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2006 Kia, check engine light is on. It has been starting rough intermittently. Once it's started it runs fine. I have had issues with the check engine light turning on and off basically since I bought the car. When it was still under warranty, the dealership replaced pretty much the whole exhaust system, fuel tank, and even the car's computer! But the check engine light kept coming on. Kia even had a specialist engineer come in from California to look at it because they couldn't figure it out. (I'm in Milwaukee).

For a while, it would come on and then go off, but now it seems to be staying on. I'm hesitant to get it fixed, because it seems they couldn't find the problem before. What they said was that the check engine light will go off when they fix something and "it resets itself". Then, if there is still an issue, it will turn on again after a certain length of time or # XXXXX miles. Meaning, they could have never fixed the issue - the light was just going off because they "reset" it after replacing a part.

Is this just a defect of the '06 optima that the check engine light comes on? I thought it wasn't an issue unless it's flashing. Now I'm wondering if my rough starts have to do with the check engine light.

Did you still need help?

What is the code number in the computer?
Customer: replied 6 years ago.
I don't know...they said it was coding for emissions. That's all I know!
COuld you call them and get the code for me?
Customer: replied 6 years ago.

Hmm, that was years ago, don't know if they'd have it. I looked and I do have all the paperwork. What would the code look like? There are several series of numbers but they may be just dealership codes for parts? It says cause: CO6 and CO7. Does that make sense?


Otherwise I suppose I'd have to take it in to get a code reading again. Any place I can do that that won't charge me $50 for it?

Ok.. do this.

Take it to your local auto parts store and get it scanned. THey will scan it for free. Auto zone or advanced auto should do this for you. The code will be something like this.

P0300, P0171 or P0420

ONce you have the code number, just get back to me and we can continue.
Customer: replied 6 years ago.
Okay, I'll get that done this weekend and get back to you. Thanks!
You bet!

I will be waiting for your reply!
Customer: replied 6 years ago.
Okay, got the code. P0301. "Cylinder 1 misfire" They said it is likely an issue with a spark plug or the cord that connects the spark plug is corroded or disconnected. Your thoughts?
HA! YES! I would agree!

When was the last time the engine was tuned up? No, not just plugs, but a full tune up! The whole nine yards! Any part of the secondary ignition will do this including the ignition coil or coils! This sounds like a classic ignition misfire! They usually go bad under a load like under acceleration, but can be noticeable at any time. It is very important to have your engine equipped with good tune up parts or you may be causing damage to other components of you car like the catalytic converter which can be expensive!

Possible causes:

Ignition misfire causes by any bad tune up part and or ignition coil or coils.
Bad spark plugs, spark plug wires and cap and rotor (if equipped)
Wrong tune up parts spark plug, wires etc...

Insulator cracks.
Improper gap.
Burned electrodes.
Heavy deposits.

The quickest way to check the ignition components, is by looking closely for leaking secondary voltage. Visual look at all the tune up parts to see if you can see any sparks coming from any of the wires or coil (or coils) when the vehicle is running. If not, you can put your hand on the coil/coils and wires when the engine is running and see if you feel any small voltage leaking form the tune up parts. Check spark plug wires by connecting ohmmeter to ends of each wire in question. If meter reads over 30,000 ohms, replace wire(s).
ALso, with engine running, spray coils and plug wires with fine water mist to check for shorts.

It will leak secondary ignition voltage from the tune up parts caused by high resistance from carbon tracking if they are bad. This is very common if the tune up parts are not changed regularly!

If any is found, the tune up parts are simply bad an will need to be replaced! If none is found than you can spray a mist of water on the tune up parts when the engine is running and see if that causes the engine to stumble or run rough at all. Again, if it does, the tune up parts are bad and will need to be replaced!
Amedee and 6 other Kia Specialists are ready to help you
Customer: replied 6 years ago.

I've never had an engine tune up. Hopefully it won't cost an arm and a leg! The person at Advanced Auto did recommend a good mechanic, so I'll have to get it in next weekend and get it checked out.


Thanks for your help!

You bet!

HAve a great weekend!