2021-2025 Hyundai P218100 Cooling System Performance TSB

Some 2021-2025 Hyundai Elantra, Kona, and Sonata Hybrid vehicles equipped with 2.0L engines may experience a Hyundai P218100 cooling fault, triggering a warning lamp. This issue is specifically linked to the Integrated Thermal-Management Module (ITM) and its thermostat.

Symptoms

Owners may notice a warning lamp illuminated on their dashboard. This light indicates a problem with the vehicle's cooling system performance.

Fault Codes / DTCs

This issue is primarily identified by the Diagnostic Trouble Code (DTC) P218100, which signifies a "Cooling System Performance" fault.

Diagnosis / Trigger Conditions

The Hyundai P218100 cooling fault is related to the Integrated Thermal-Management Module (ITM). The problem stems from the thermostat within the ITM potentially opening prematurely. A confirmed customer concern and related symptom are required before any repair work is performed under this TSB.

Important Warnings and Owner Advisories

• Warranty Coverage: This field action is covered under the 8-year/80,000-mile Emissions Warranty, provided the vehicle is within the mileage and warranty start date limits. If outside warranty, dealers may submit a goodwill request.
• Repair Justification: Repair work requires a customer concern and a confirmed symptom. Claims submitted without proper justification may be debited.
• Coolant Type: Ensure that any green antifreeze/coolant is fully evacuated and replaced with pink antifreeze/coolant (P/N 00232-19098) if applicable.
• ECU Update Precautions:
  • The vehicle's battery charge must be above 11.0 Volts and the tablet's battery charge above 30% to prevent update failure.
  • DO NOT leave headlamps in auto mode or turn on any accessories during the update.
  • The ignition switch must be in the ON position.
  • DO NOT disconnect any cables from the vehicle or scan tool during the update.
  • DO NOT start the engine or place the vehicle in Ready mode during the update.
  • DO NOT turn off the ignition switch during the update.
• Cooling System Safety: NEVER remove the radiator cap when the engine is hot, as serious scalding can occur from escaping hot fluid under pressure.
• Post-Repair Bleeding: Failure to follow the ITM bleeding procedure may lead to air pockets and engine overheating.

Repair Procedure Summary

The repair for the Hyundai P218100 cooling fault involves two main components: a mechanical fix to the ITM thermostat and an ECU software update.

1. ITM Thermostat Spring Installation:

   • The Integrated Thermal-Management Module (ITM) is removed from the vehicle.
   • A new spring (Part Number 25689-2J001QQH) is inserted into the ITM thermostat hole.
   • A new thermostat housing gasket (Part Number 25623-2J000QQH) is installed, ensuring surfaces are clean and the gasket is properly seated.
   • The ITM assembly is reinstalled. Technicians are advised to hold the spring down to prevent it from falling out during installation.
   • When reconnecting the ITM connector, ensure no water, oil, or foreign material is present.
   • All remaining components are reinstalled in reverse order of removal.

2. ECU Software Update:

   • The ECU update must be completed before the coolant bleeding process.
   • The update is performed using a GDS (Global Diagnostic System) tablet in Manual Mode.
   • The technician selects the correct engine system and ECU sub-event (e.g., 1213 for Sonata Hybrid, 1214 for Elantra, 1216 for Kona OS, 1287 for Kona SX2).
   • If the update fails, the power connector from the in-cabin fuse box or the negative (-) 12V battery terminal must be disconnected for at least 5 seconds, then reconnected, and the update retried.
   • After the update reaches 100% completion, the ignition is cycled OFF for 10-30 seconds to reset the control unit.
   • A screenshot of the ECU Update "Success" screen is required for digital documentation.
   • An "All Systems Fault Code" search is performed, and any incidentally generated DTC history is erased.

3. Cooling System Bleeding:

   • The engine is started or placed in Ready mode to confirm proper operation.
   • The ITM Coolant Filling Method is performed using GDS to fully bleed the cooling system. This involves entering the Integrated Thermal Module Coolant Filling Mode.

Required Tools or Parts

• Spring: Part Number 25689-2J001QQH (Qty: 1)
• Gasket - Thermostat Housing: Part Number 25623-2J000QQH (Qty: 1)
• Pink Antifreeze/Coolant: Part Number 00232-19098 (Qty: 1 gallon, select only one)
• Diagnostic Tools:
  • VCI 3 (GOVHNNN06)
  • VCI 2 (G1XDDMN001) - can be used for updates but is no longer orderable.

Warranty Information

This field action is covered under the 8-year/80,000-mile Emissions Warranty. Claims must be submitted as "Campaign" type. Dealers will be reimbursed for 1 gallon of coolant under each operation code. Incident parts are subject to callback, and claims may be debited if parts are not returned.

NHTSA ID: 11027036