Follow either of these procedures:
Kia Niro (DE HEV) Owners Manual: Transmitter precautions
The transmitter will not work if any of the following occurs:
The ignition key is in the ignition switch. (for folding key)
Another vehicle’s smart key is being operated close to your vehicle.
You exceed the operating distance limit (about 10 m [30 feet]).
The battery in the transmitter ...
Kia Niro 2017 (DE HEV) Service Manual: Auxiliary 12V Battery Description and operation
Description
1.
The CMF(Closed Maintenance Free) battery is, as the name implies, totally
maintenance free and has no removable battery cell caps.
2.
The CMF(Closed Maintenance Free) battery does not require water replenishment
for the rep ...