(Bloomberg) -- Fiat Chrysler Automobiles NV is recalling about1.4 million cars and trucks equipped with radios that arevulnerable to hacking.

The company said in a statement it has blocked unauthorizedremote access to certain vehicles systems with a network-levelimprovement on Thursday.

Fiat Chrysler was already distributing software to insulateconnected vehicles from illegal remote manipulation afterWired magazine published a story about softwareprogrammers who were able to take over a Jeep Cherokee being drivenon a Missouri highway. Fiat Chrysler reiterated that it’s not awareof any real-world unauthorized remote hack into any of itsvehicles.

[Related: Fiat Chrysler offers software patch after hackerscontrol Jeep]

It stressed that no defect was found and that it’s conductingthe campaign out of "an abundance of caution."

The recall covers almost a million more models than thoseinitially identified as needing a software patch. The actionincludes 2015 versions of Ram pickups, Jeep Cherokee and GrandCherokee SUVs, Dodge Challenger sports coupes and Vipersupercars.

Affected customers will receive a USB device to upgrade theirvehicle’s software with additional safety features, beyond thenetwork-level measure.

Shares of Fiat Chrysler fell 1.4 percent to $15.32 at 11:07 a.m.New York time. The stock had gained 34 percent this year throughThursday.

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