Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSKIA2013FORTE KOUP EX, STANDARD TRANSREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM DIAGNOSIS (1 OF 3) - EXCEPT SULEVDTC P0128: COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTAT REGULATING TEMPERATURE)GENERAL INFORMATIONDTC DETECTING CONDITION

2013 Kia Forte Koup EX, Standard Trans

General Information: DTC Detecting Condition

2013 Kia Forte Koup EX, Standard TransSECTION DTC Detecting Condition

DTC DETECTING CONDITION AND POSSIBLE CAUSES

Item	Detecting Condition	Possible Cause
DTC Strategy	Coolant temp. not reached warm up state	Faulty cooling system Faulty ECT sensor Poor connection or damaged harness
Enable Conditions	Fuel-cut off phase <20% Low load phase < 50% 11V < Battery voltage < 16V Intake air temperature decrease compared to Start Intake air temperature > -10°C (-14°F) -10°C (14°F) < Coolant temperature at start < 54.4°C (131°F) -10°C (14°F) < Intake air temperature at start No high engine speed (4800 RPM) with vehicle stopped No relevant failure Ambient temperature > -10°C (-14°F) Percentage of high vehicle speed phase (Vehicle speed > 87 mph) < 90%
Threshold Value	Measured coolant temp. < 74°C (165°F) When modeled coolant temp. > 85°C (185°F)
Diagnostic Time	10~30 min. depending on coolant temperature at start and driving pattern
Mil On Condition	2 Driving Cycles

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.