Analog UV sensor displaying incorrect values in serial monitor (GUVA-S12SD)

Question

Using Arduino Uno and a GUVA-S12SD sensor (https://www.adafruit.com/product/1918).

Here's my circuit. 5V into sensor+, GND into sensor-, A0 to sensor out.

Here's my code:

void setup() 
{
  Serial.begin(9600);
}
 
void loop() 
{
  float sensorVoltage; 
  float sensorValue;
  float uvIndex;
 
  sensorValue = analogRead(A0);
  Serial.print("Analog out: ");
  Serial.println(sensorValue);

  // 5 because 5V
  sensorVoltage = sensorValue * (5.0 / 1023.0);
  Serial.print("Output voltage: ");
  Serial.println(sensorVoltage);

  uvIndex = sensorVoltage / 0.1;
  Serial.print("UV Index: ");
  Serial.println(uvIndex);

  Serial.println();

  delay(1000);
}

Here's a sample from the serial monitor. The values stay about the same regardless of where I am in my house (in a sunny room, in the dark bathroom, etc.).

Analog out: 853.00
Output voltage: 4.17
UV Index: 41.69

Analog out: 853.00
Output voltage: 4.17
UV Index: 41.69

Analog out: 853.00
Output voltage: 4.17
UV Index: 41.69

Analog out: 853.00
Output voltage: 4.17
UV Index: 41.69

Output voltage is supposed to be very low. The UV index maxes out at around 11 - so 41 is too high. I checked what it is in my city right now, and it's 3. So this is super wrong. I don't have a multimeter to test with right now.

Any ideas about what could be going on? Did I order a bad sensor?