Since it was launched in December 2010, the Nissan Leaf electric car has been offered with a telematics system that relies on a cellular connection.
NissanConnectEV, previously known as Carwings, lets owners monitor functions like climate control and charging remotely, and find nearby charging stations.
When the system launched, it was based on a 2G network that is now being phased out.
Network operator AT&T plans to switch off its 2G service in North America at the end of the year and re-purpose the frequencies, as the number of 2G cellphone users has declined dramatically.
Nissan is now encouraging drivers of older Leafs—including cars from model years 2011 to 2015—to upgrade so that their ability to access the system doesn't vanish with the 2G network.
These drivers will need to upgrade the onboard telematics-control units (TCUs) in their cars to communicate with the 3G network that will take up the bandwidth previously occupied by AT&T's 2G network.
The automaker now says that upgrade will cost owners of 2011-2014 Leaf electric cars $199, according to Transport Evolved.
Nissan previously said it would cover "a portion" of the parts and labor costs associated with upgrading the TCU in these models.
It has also said it will cover the entire cost of the TCU upgrade for 2015 models.
Only Leaf SV and SL models are affected, as the base Leaf S from these model years was not equipped with the telematics feature.
With just 24 days left before AT&T shuts off its 2G network on December 31, Nissan hasn't left much time for owners to get the upgrade without any interruption in service.
Owners may also be less than enthusiastic about paying an extra fee to keep a service that has had its share of issues.
Users have complained of spotty connectivity, and earlier this year a cybersecurity consultant found a security flaw in the system's associated app.