P0303 on KIA OPTIMA
What P0303 Means on Your KIA OPTIMA
Real KIA OPTIMA Owner Reports (Source: NHTSA Complaints Database)
"The contact owns a 2012 Kia Optima. The contact stated while driving approximately 70 MPH, the check engine warning illuminated, and the vehicle lost motive power. The contact stated that the engine was running however, the vehicle failed to respond as needed."
"On Sunday, September 21st, 2025, my 2013 Kia Optima EX suffered sudden catastrophic engine failure while driving on the highway. The check engine light was flashing, the car misfired badly, lost complete power, and became unsafe to operate. The vehicle was then towed to Wagner Kia of Shrewsbury, MA."
"Engine is failing and using over 3 quarts of oil every 700-100 miles. Spark Plugs have become oil fouled and replaced all 4 spark plugs June 11th, 2024 and replaced all 4 spark plugs again January 12th, 2025."
Data from NHTSA Vehicle Complaints Database. All reports are filed by vehicle owners directly with the U.S. Department of Transportation.
Common Causes of P0303 on KIA OPTIMA
Percentages based on NHTSA complaint component analysis for this vehicle.
Complaint Trend by Year
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if your vehicle is covered.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50-$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2-3 quotes. Dealer vs independent shop prices often differ 30-50% for the same repair.