What does this code mean?
The warm-up performance did not meet the monitor's expectation. Check coolant level only when the engine is cool, compare temperature readings from a cold start, and assess the thermostat and cooling-fan operation. Climate, sensor accuracy and vehicle calibration matter. Never open a hot pressurised cooling system.
Sources and interpretation [1]
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer communications
3Original wording in English
KIA
Reported code forms P0128
TECHNICAL SERVICE BULLETIN: SERVICE ACTION: GAMMA 1.6L-T GDI ULEV MIL ON DTC P0128 AND/OR DTC P0300~304 JUDGEMENT LOGIC IMPROVEMENT (SA419) - This bulletin provides the procedure to improve the logic of the Engine…
KIA
Reported code forms P0128
TSB - SERVICE ACTION: ELECTRIC THERMOSTAT REPLACEMENT (SA308) - This bulletin provides the procedure to replace the electric thermostat on 2017MY Forte (YDm) 2.0L MPI vehicles, produced from May 23, 2016 through March…
KIA
Reported code forms P0128
PITSTOP: THERMOSTAT RE-INSTALLATION PROCEDURE - REPEAT REPAIR (DTC P0128) - WHEN DIAGNOSING A FORTE RETURNING WITH A REPEAT DTC P0128 AFTER REPLACEMENT OF THE THERMOSTAT, REMOVE THE THERMOSTAT HOUSING TO VERIFY IF THE…
Check vehicle applicability
7A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Kia | FORTE | 2020 |
| Kia | FORTE | 2019 |
| Kia | FORTE | 2017 |
| Kia | FORTE | 2013 |
| Kia | FORTE | 2012 |
| Kia | FORTE | 2011 |
| Kia | FORTE | 2010 |
Historical records · 4 · Historical vehicle association; OBD-II compatibility is not established by this record.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Sources and interpretation
These explanations are editorial summaries of the linked manufacturer material. PDF page numbers count from the first file page. Original publications are in English; translations are reference aids. A cited edition is not a claim that it is the manufacturer's latest instruction.
- 2024–2025 MY OBD System Operation Summary for Gasoline Engines ↗
Ford Motor Company · PDF page(s) 71 ·
Source check date · 2026-10-27
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.