P0303 on Honda Civic
Cylinder 3 Misfire Detected
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Honda Civic 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 P0303.
- 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 P0303 Means on Your Honda Civic
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.
Real Honda Civic Owner Reports
Source: NHTSA Complaints Database
"Driving on highway to work when check engine light came on in addition to "Emissions System Problem", "Hill Start Assist", "Power Steering Issue", etc. When scanned for codes it showed misfire codes P0300, P0301, P0302, P0303, P0304."
"The contact owns a 2018 Honda Civic. The contact stated while driving approximately 20 MPH, several unknown warning lights illuminated and the vehicle started to idle very rough. The contact had taken the vehicle to a local dealer however, the vehicle was not diagnosed."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Honda Civic
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.