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P0128 on HYUNDAI SONATA

Severity
Medium
NHTSA Reports
2
Most Affected
2015, 2016

What P0128 Means on Your HYUNDAI SONATA

Real HYUNDAI SONATA Owner Reports (Source: NHTSA Complaints Database)

"[XXX] THERMOSTAT ERROR REPORT P0128 REPLACED THERMOSTAT AND FLUSHED COOLANT ON 5.28."

— 2015 HYUNDAI SONATA owner • ENGINE • Filed 05/24/2024

"Purchased car with just under 97000 miles. Was working terrific. Time for the first oil change and 2 miles after the change the car froze and went limp. Traveling 45 miles per hour it recorded a trouble code on my monitoring device. P0605 - ROM error and the car was dead."

— 2016 HYUNDAI SONATA owner • ENGINE • Filed 03/20/2023

Data from NHTSA Vehicle Complaints Database. All reports are filed by vehicle owners directly with the U.S. Department of Transportation.

Common Causes of P0128 on HYUNDAI SONATA

100%

Percentages based on NHTSA complaint component analysis for this vehicle.

Complaint Trend by Year

2015
1
2016
1

What To Do Next

  1. 1
    Check for recalls on YOUR VIN

    Go to nhtsa.gov/recalls and enter your VIN. Free repairs if your vehicle is covered.

  2. 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. 3
    Compare repair quotes

    Get 2-3 quotes. Dealer vs independent shop prices often differ 30-50% for the same repair.

P0128 on Other Vehicles

Data sourced from the National Highway Traffic Safety Administration (U.S. Department of Transportation) and the SAE J2012 OBD-II standard. Code definitions follow the SAE J2012 / ISO 15031-6 standard. Owner reports are filed directly with NHTSA by vehicle owners. This information is provided for educational purposes only and should not replace professional automotive diagnosis. Always consult a qualified mechanic for vehicle repair decisions.

Last updated: March 2026