Since it was launched as a 2011 model, the Nissan Leaf electric car has been offered with a telematics system that relies on a cellular connection to deliver information to the driver.
NissanConnectEV, formerly known as Carwings, lets owners monitor functions like climate control and remote charging. it also compiles a driving history from relevant data.
But in many of the existing Leafs, that system relies on a soon-to-vanish 2G cell network.
So Nissan is undertaking a campaign to get customers to upgrade their cars before 2G is phased out completely.
AT&T, Nissan's network provider, plans to shut down its 2G cellular network completely on December 31.
The company is expected to begin "sunsetting" the 2G service before that, meaning Leaf owners in certain parts of the country may be shut out of NissanConnectEV well before the end of the year.
Cars will require upgrades to the onboard telematics-control units (TCUs) to communicate with the 3G and 4G networks that will take up the bandwidth previously occupied by AT&T's 2G network.
For 2011 through 2014 Leaf models, Nissan will cover "a portion" of the parts and labor costs associated with upgrading the TCU.
The carmaker will foot the entire bill for upgrades to 2015 Leaf models.
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Nissan did not specify the actual cost of the upgrade, but in an e-mail to owners, it said additional information would be available in late summer 2016.
It also noted that customers can continue to sign up for NissanConnectEV using the outgoing 2G connection until June 30.
It's possible that Nissan wants to wait until after that cutoff point to begin upgrading the cars, so that it can address all affected vehicles in one coordinated campaign.
Approximately 55,000 cars could be affected, including 20,000 from the 2011 and 2012 model years, and 35,0000 from 2013 through 2015.
The announcement comes shortly after Nissan shut off access to the mobile app for NissanConnectEV, after a potential security flaw was brought to its attention.
Australian cybersecurity consultant Troy Hunt found that the app could be hacked, potentially giving outsiders access to certain functions like climate control.
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Nissan's own investigation confirmed that the server connected to the app lacked adequate security, meaning commands could be sent through it via a "non-secure route."
The app had allowed owners to do things like change the climate-control settings remotely, and check charging and vehicle information.
All of these functions can still be controlled manually from the car itself, and the affected vehicles remain safe to drive, Nissan said.
[hat tip: Brian Henderson]