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K. Wiggins
K. Wiggins, ASE Certified Technician
Category: Kia
Satisfied Customers: 2912
Experience:  ASE Certified Technician, Associates Degree in Automotive Technology, 15+ years in the trade
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I have a 2002 KIA Optima SE, and my check engine light came on and the diagnostic at my lo

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I have a 2002 KIA Optima SE, and my check engine light came on and the diagnostic at my local auto parts store said that it was the knock sensor. I bought a new sensor and no one I have taken it to has been able to find it. Minus the KIA Dealership. Is it worth the $100 to take it in to the dealership to be diagnosed? If the car is shot, is there anyway to know that without taking it to the dealership to essentially be put down?
Hello, do you happen to have the actual code numbers from the parts store diagnostics?
Customer: replied 3 years ago.

No, they just told me that the knock sensor was the only code that came up. I can run it down the street real quick and let you know.

Customer: replied 3 years ago.

P0401 EGR flow insufficient, P0442 Evap emission system leak, P0325 Knock Sensor

May I ask how many miles are on it and how does it run in general. From the way it looks so far I see no need to junk it
Customer: replied 3 years ago.


Customer: replied 3 years ago.

It seems to run fine except for the acceleration and shifting issues. Which I was told could all be related to the knock sensor being bad. However, I also heard that the knock sensor could just be doing its job and that something could be wrong with the engine.


Thanks for the information. The knock sensors job is to retard the timing under a situation where engine damage could occur, (heavy engine load with low octane fuel etc) A Knock sensor code can also be triggered by an engine misfire. Since we have no misfire in the stored trouble codes we can eliminate that.
So to put it this way there's likely no other problem with the engine other than an issue with the EGR flow (could be a bad vacuum line or EGR valve) A large EVAP leak (again his is likely a bad hose or valve) and the knock sensor or the wiring going to it or the ecm.
All of the above is not hard to to check with the appropriate scan tool and a smoke machine to leak check the evap system. If no local independent shops will touch it it's well worth the fee to have KIA diagnose it. If you click here you can see what is involved in testing these things.
Replacing the knock sensor itself is not a terribly expensive job. Book time is 30 minutes and the part lists for around 85.00.
With the low mileage on your vehicle I would go ahead and look into having it fixed. I honestly see this whole repair at a worse case scenario being no more than 500.00.
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