SGP41 I2C Address: 0x59

How to set the address

There is no address pin: the address is set at the factory, so it is always 0x59.

Devices that use the same addresses

Two devices on the same bus can’t answer on the same address. These modules from our list also use 0x59:

Device	What it is	Shared address
PCA9685	16-channel 12-bit PWM / servo driver	0x59
SGP40	VOC index gas sensor	0x59

If two of them end up on the same address, move one with its address pin, put one behind a TCA9548A multiplexer (0x70–0x77), or use a second I²C bus: the ESP32, ESP32-S3 and RP2040 have two I²C controllers (the ESP32-C3 has one).

Check your whole bus →Add the SGP41 and your other modules: the checker finds conflicts, suggests free addresses and sizes the pull-ups.

7-bit and 8-bit address

I²C addresses are 7 bits long. Some datasheets and libraries write them as 8-bit numbers, with the read/write bit added on the right: that is why the same chip can appear as 0x59 or 0xB2. Arduino’s Wire library and ESPHome use the 7-bit form.

7-bit	Binary	8-bit write	8-bit read
0x59	1011001	0xB2	0xB3

Check that it answers

Upload this sketch with the SGP41 wired to SDA and SCL: it tries every address the chip can use and prints the one that answers. On an ESP32 the default pins are GPIO21 (SDA) and GPIO22 (SCL); on an Arduino Uno, A4 and A5.

#include <Wire.h>

const byte ADDRS[] = {0x59};

void setup() {
  Serial.begin(115200);
  Wire.begin();
  for (byte a : ADDRS) {
    Wire.beginTransmission(a);
    if (Wire.endTransmission() == 0) {
      Serial.print("SGP41 answers at 0x");
      if (a < 0x10) Serial.print('0');
      Serial.println(a, HEX);
      return;
    }
  }
  Serial.println("No answer: check the wiring");
}

void loop() {}

In ESPHome the bus is scanned at boot (scan: true is the default): the log lists every address that answers.

i2c:
  sda: GPIO21
  scl: GPIO22
  scan: true

Pull-up resistors

SDA and SCL need pull-up resistors to the supply. Many breakout boards already carry them, often 4.7 kΩ or 10 kΩ, and with several boards on the bus they add up in parallel. The I²C checker works out the allowed range for your bus voltage and speed.

Frequently asked questions

What is the I2C address of the SGP41?

0x59. It is fixed: there is no address pin.

Can I use more than one SGP41 on the same bus?

Not directly: the address is fixed, so two would clash. Put each one on a different channel of a TCA9548A multiplexer, or use a second I²C bus.

Why doesn’t the SGP41 show up in an I2C scan?

Check, in this order: SDA and SCL not swapped; ground shared between the boards; pull-up resistors on SDA and SCL; the module powered at the voltage it is made for; and that your code uses the 7-bit address (0x59), not the 8-bit one (0xB2).

Addresses checked against the SGP41 datasheet.

SGP41 I²C address