SIM 900: inaccurate date/time data

Greetings!

I would like to ask for help because my GSM Module is not working very well. It gives invalid data when I try to get the time and date

void setup() {
  Serial.begin(9600);
  Serial1.begin(9600);
}
void loop() {
   Serial1.print("AT+CCLK?\r");
  while (Serial1.available() > 0) {
    int Years = Serial1.parseInt();
    int Months = Serial1.parseInt();
    int Days = Serial1.parseInt();
    int Hours = Serial1.parseInt();
    int Mins = Serial1.parseInt();
    int Secs = Serial1.parseInt();
    int Nu = Serial1.parseInt();

    Serial.print(Years);
    Serial.print("/");
    Serial.print(Months);
    Serial.print("/");
    Serial.print(Days);
    Serial.print("  ");
    Serial.print(Hours);
    Serial.print(":");
    Serial.print(Mins);
    Serial.print(":");
    Serial.print(Secs);
    Serial.println();
  }
delay(5000);
}

I get this kind of data some of the time:

0/0/5175,0:0:0

Before trying to parse the data why don’t you try first to print the answer you get
Once you know what you have (or not) you can decide how to parse it

You should read Serial Input Basics