P0304 on Hyundai Elantra
Cylinder 4 Misfire Detected
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Hyundai Elantra context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0304.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0304 Means on Your Hyundai Elantra
P0304 is a diagnostic trouble code indicating: Cylinder 4 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.
Real Hyundai Elantra Owner Reports
Source: NHTSA Complaints Database
"Drove vehicle to dealer, boucher hyundia of waukesha after the check engine light would go on and off with codes p2096 and p0304. codes are related to cylinder 3 and 4 misfires. dealer found engine making a noise from lower end and recommends an engine replacement."
"Check engine light on with diagnostic error code P0304 cylinder 4 misfire detected ignition coil"
"I am filing this Vehicle Owner's Questionnaire (VOQ) regarding critical safety defects in my 2018 Hyundai Elantra related to: - Recurrent ignition coil pack failures (3 replacements since 10/2018) - Engine stalling at low speeds (6 incidents since 10/2018) - Dealer refusal to apply TSB 20-01-008H EC"
"I purchased my 2019 Hyundai Elantra from a third-party dealer (Mike Carlson Motor Company in Haltom City, TX) on [XXX]. I have kept the oil changed on a regular basis since I purchased it."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Hyundai Elantra
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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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.