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Service bulletin TSB_ENG258

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id11023283
Published by NHTSA2025-09-23
Manufacturer's numberTSB_ENG258
Manufacturer's date2025-09-13
Campaign id or software versionSA621
NHTSA componentENGINE
Manufacturer's systemENG

NHTSA's summary

TECHNICAL SERVICE BULLETIN: SERVICE ACTION: ECM JUDGEMENT LOGIC IMPROVEMENT FOR DTC P218100 (SA621) - This bulletin provides information to upgrade the Engine Control Module (ECM) system software on certain 2025MY K4 (CL4m) vehicles produced from July 03, 2024 through April 28, 2025 equipped with an Nu 2.0L MPI engine. The vehicles affected may exhibit a MIL ‘ON’ with DTC P218100 stored under certain driving conditions such as high-load, high-speed driving in low temperature environments. There are no drivability or other symptoms associated with this condition. High-load control logic helps to lower the coolant temperature by allowing the valve of the Integrated Thermal Module (ITM) to fully open the radiator port during rapid acceleration.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Trouble codes named

P2181

Vehicles listed
KIA K42025

Listing a model year does not mean every vehicle of it is concerned: the document says which.

Recalls for the same vehicles and component
25V5480002025-08-25. ENGINE AND ENGINE COOLING:CRITICAL FASTENERS

A recall listed here may apply to some of the same vehicles. Only the manufacturer can say whether it applies to one vehicle.

Other bulletins for the same vehicles and component
OTA_SA6212025-12-10. Over-the-air update. RELEASE NOTES: OVER-THE-AIR: SERVICE ACTION SOFTWARE UPDATE FOR WARNING LIGHTS (SA621) - This Over-the-Air (OTA) software update is designed to update the Engine Control Unit (ECU) logic of certain 2025 K4 vehicles. This update improves the processing logic of the Engine Control Unit (ECU) to reduce the unintended display of warning lights.