exfatfsck: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/sbin/exfatfsck - from package: exfat-utils

You may install the required package with command apt-get install {package}

Error in other languages:
exfatfsck: bevel nie gevind nie
exfatfsck: comandă negăsită
exfatfsck: comando não encontrado
exfatfsck: commande introuvable
exfatfsck: command not found
exfatfsck: käsku ei ole
exfatfsck: không tìm thấy lệnh
exfatfsck: komanda nerasta
exfatfsck: Kommando nicht gefunden.
exfatfsck: kommandot finns inte
exfatfsck: komut yok
exfatfsck: nie znaleziono polecenia
exfatfsck: níor aimsíodh an t-ordú
exfatfsck: no se encontró la orden
exfatfsck: no s'ha trobat l'ordre
exfatfsck: opdracht niet gevonden
exfatfsck: parancs nem található
exfatfsck: perintah tidak ditemukan
exfatfsck: príkaz nenájdený
exfatfsck: příkaz nenalezen
exfatfsck: команда не найдена
exfatfsck: командата не е открита
exfatfsck: 命令找不到
exfatfsck: コマンドが見つかりません