DTC B1426-4B: Right Front Cooled/Heated Seat Thermal Electric Device #1 - Over temperature: Action

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2018 Land Rover Range Rover, 2017 Land Rover Range Rover, 2016 Land Rover Range Rover, 2015 Land Rover Range Rover, and 2014 Land Rover Range Rover. However, it is still accessible from the selected car via links, so may be relevant.

Check the airflow to the front right seat backrest climate assembly thermal electric device is not blocked
Using the JLR approved diagnostic equipment, clear the DTCs and retest. For further symptom driven diagnostic flow. Refer to the relevant Seating - Diagnosis and Testing - Vehicles With: Climate Controlled Seats, service information.