P0420 on HYUNDAI SONATA
What P0420 Means on Your HYUNDAI SONATA
Real HYUNDAI SONATA Owner Reports (Source: NHTSA Complaints Database)
"The contact owns a 2017 Hyundai Sonata. The contact stated while driving at an undisclosed speed, the vehicle stalled with the check engine warning light illuminated. Additionally, there was white smoke coming from the engine compartment and the exhaust."
"Multiple critical mechanical and safety issues have occurred with my 2018 Hyundai Sonata Sport. The vehicle has experienced persistent engine misfire, a severe oil leak, emissions system failure, and extensive paint deterioration."
"Coding P0507 Idle air control system Rpm higher than expected P0441 Evaporator emissions incorrect purge flow P0420 Catalyst system below threshold"
Data from NHTSA Vehicle Complaints Database. All reports are filed by vehicle owners directly with the U.S. Department of Transportation.
Common Causes of P0420 on HYUNDAI SONATA
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.