P0303 on HYUNDAI SONATA — Cylinder 3 Misfire Detected

Q: "What does P0303 mean on a HYUNDAI SONATA?"

"P0303 indicates: Cylinder 3 Misfire Detected. This is a ignition system code. 3 HYUNDAI SONATA owners have reported this to NHTSA."

Q: "What are the most common causes of P0303 on HYUNDAI SONATA?"

"Based on 3 NHTSA reports, the most commonly cited components are: Engine, Power Train,Unknown Or Other,Engine. These percentages are based on the component field in owner complaints."

Q: "Is P0303 serious on my HYUNDAI SONATA?"

"Of 3 NHTSA reports for this code on HYUNDAI SONATA, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic."

Q: "What should I do if my HYUNDAI SONATA shows P0303?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

What P0303 Means on Your HYUNDAI SONATA

P0303 is a diagnostic trouble code indicating: Cylinder 3 Misfire Detected. This code relates to the ignition system system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

3 HYUNDAI SONATA owners have reported this issue to NHTSA across model years 2015-2016. Most reports come from the 2016, 2015 model years. The most commonly reported component is Engine (66.7% of reports).

Real HYUNDAI SONATA Owner Reports

Source: NHTSA Complaints Database

"Our 2015 Sonata has experiencing Engine failure several times due to excessive and irregular oil consumption."

— 2015 HYUNDAI SONATA owner · POWER TRAIN,UNKNOWN OR OTHER,ENGINE · Filed 01/22/2025

"Vehicle has been repaired due to broken valve. Vehicle was unsafe to drive. Valve burnt at 70 mph. Car threw misfire code P0303 and started shaking. This issue could have caused an accident. Valves were replaced at Young Hyundai in Ogden Utah."

— 2016 HYUNDAI SONATA owner · ENGINE · Filed 11/20/2024

"I changed out every cylinder, axel, within 6 months and now on March 22, 2023, they said I needed a new engine. P0300, P0303 MISFIRE. They said the car misfired. I thought that's why they changed all the cylinders. WHY DID THIS HAPPEN? My car has been parked in the garage."

— 2016 HYUNDAI SONATA owner · ENGINE · Filed 03/09/2023

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

1

'15

2

'16

Common Causes on HYUNDAI SONATA

Based on NHTSA complaint component analysis for this vehicle.

ENGINE 66.7%

POWER TRAIN,UNKNOWN or OTHER,ENGINE 33.3%

What To Do Next

1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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.
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.

Frequently Asked Questions

What does P0303 mean on a HYUNDAI SONATA? ▾

P0303 indicates: Cylinder 3 Misfire Detected. This is a ignition system code. 3 HYUNDAI SONATA owners have reported this to NHTSA.

What are the most common causes of P0303 on HYUNDAI SONATA? ▾

Based on 3 NHTSA reports, the most commonly cited components are: Engine, Power Train,Unknown Or Other,Engine. These percentages are based on the component field in owner complaints.

Is P0303 serious on my HYUNDAI SONATA? ▾

Of 3 NHTSA reports for this code on HYUNDAI SONATA, none involved a crash or fire. However, any diagnostic code should be evaluated by a qualified mechanic.

What should I do if my HYUNDAI SONATA shows P0303? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.