2021 Mercedes-Benz AMG GT Engine Thermostat Extended Warranty

Mercedes-Benz USA, LLC (MBUSA) has extended the warranty coverage for the engine thermostat, including associated software updates, on the 2021 Mercedes-Benz AMG GT. This extension is in response to a condition where a sealing ring in the engine thermostat may detach, leading to delayed engine coolant heating and potentially illuminating the check engine Malfunction Indicator Lamp (MIL). This extended warranty ensures that owners of affected vehicles receive necessary repairs for this specific issue.

Symptoms

Owners of the 2021 Mercedes-Benz AMG GT may notice the following symptoms related to a faulty engine thermostat:

• A delay in the heating of the engine coolant.
• The check engine "Malfunction Indicator Lamp ('MIL')" illuminating on the dashboard.

Fault Codes / DTCs

When diagnosing the Mercedes-Benz AMG GT engine thermostat issue, technicians may find the following Diagnostic Trouble Code (DTC) and damage codes:

• P012800 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

Associated damage codes include:

• 20102 - Insert, coolant thermostat
  • 52 - Does not operate correctly
  • 41 - Hard closing
• 20103 - Housing/cover, coolant thermostat
  • 73 - Electrical fault
• 2030T - Heating element, coolant thermostat
  • 53 - Insufficient effect/power
  • 73 - Electrical fault

Diagnosis

To properly diagnose the engine thermostat issue, technicians will perform several steps:

1. Connect to the XENTRY/DAS diagnostic system.
2. Check for and install any available software updates for the N3/10-Motor electronics control unit.
3. Perform a guided test for the R48 coolant thermostat heating element.
4. If the guided test indicates a problem, or if the engine serial number falls within a specific range, further repair procedures are initiated.
5. Verify the engine serial number via VeDoc and compare it against the Engine Number Table to determine if the thermostat is affected.

Repair Procedure Summary

For the 2021 Mercedes-Benz AMG GT, the repair procedure typically involves:

1. Connecting the vehicle to the XENTRY/DAS diagnostic system.
2. Checking for and performing any necessary software updates for the N3/10-Motor electronics.
3. Conducting a guided test for the R48 coolant thermostat heating element.
4. If the test fails, or if the engine serial number indicates an issue, the thermostat and R48 heating element will be replaced. This is referred to as Work Procedure A.
5. After replacement, the system is re-checked to ensure proper function.

Required Tools or Parts

Technicians will use specific tools and parts for this repair:

• Thermostat (Part Number: * - determined by VIN)
• XENTRY/DAS diagnostic system
• Charger for starter battery (for diagnostic operations)
• WIS document AR20.10-P-2461* (for basic data and specific repair instructions)

Important Warnings

Owners should be aware of the following critical information regarding this extended warranty:

• "This NCU supersedes the prior NCUs issued on December 1, 2023 and February 06, 2024 and includes additional MY 2019 AMG G63 vehicles."
• "Mercedes-Benz USA, LLC (“MBUSA”) is extending the warranty coverage on the engine thermostat (including software update) installed in certain Model Year (“MY”) vehicles (with engines M176, M177, M178) listed below from the original New Vehicle Limited Warranty of 4 years/50,000 miles to 15 years/150,000 miles (whichever occurs first)."
• "All repairs found to be functioning properly or without proper documentation will be returned and the claim debited in full."
• "Please check the VIN in NetStar/VMI before scheduling the appointment for the repair. Applicable vehicles will be visible in NetStar/VMI on December 01, 2023."
• "Reimbursement may be limited to the amount the repair would have cost if completed by an authorized Mercedes-Benz dealership and repairs performed by a non-Mercedes-Benz dealership might not be reimbursed."
• For reimbursement, "Only Mercedes-Benz replacement parts were used for the repair."
• "Reimbursement will be paid by a check from an authorized Mercedes-Benz dealership, which may take up to 60 days."

Owner Action

If you own a 2021 Mercedes-Benz AMG GT and experience symptoms of a faulty engine thermostat, such as a check engine light or delayed engine warming, you should:

• Expect to receive a letter from Mercedes-Benz notifying you of this warranty extension. Letters will be sent approximately two weeks after the posting of this News Channel Update (NCU).
• Contact an authorized Mercedes-Benz dealership to schedule an appointment for diagnosis and repair. Ensure your VIN is checked in NetStar/VMI to confirm coverage.
• If you have previously paid for a repair related to the Mercedes-Benz AMG GT engine thermostat issue, you may be eligible for reimbursement. Gather all original receipts, invoices, and repair orders that include your name, address, VIN, problem description, repair details, parts used (must be Mercedes-Benz replacement parts), DTC information (if any), and proof of payment.
• Submit your reimbursement request to an authorized Mercedes-Benz dealership.
• "Should you have any questions or concerns, please do not hesitate to open a OneTRAC case online."

Source: NHTSA ID 11013884