Gravity: O2 Sensor - Measuring 0% at ambient air - from the beginning
Vinay.Patel 2026-06-03 21:20:09 238 Views1 Replies The FAQ spoke about outputting zero readings after a long time of use, but mine is doing it straight away. What should I do? I've got this version:
https://thepihut.com/products/gravity-o2-sensor-calibrated-i2c-uart
For SEN0465, it may help to first test with the official wiki example code.
Use the default I2C setup first: SEL = 0, I2C address 0x74. If SEL or the I2C address has been changed, fully power-cycle the module before testing again.
The wiki also lists several handling notes worth checking: warm up for more than 5 minutes on first power-up, or more than 24 hours if it has not been used for a long time; do not hot-plug the probe; do not remove the white waterproof breathable membrane; avoid solvents, adhesives, paints, oils, high-concentration gases, strong airflow, shock, or vibration. Also avoid running calibration commands unless a standard gas is available, since that can affect the calibrated data.
After warm-up, the example should show the gas type and board temperature. If it reads O2 and the temperature looks reasonable, communication is probably working. Ambient air should normally be around 20-21% O2, so if it still stays at 0%, it may be worth checking the UART protocol directly with a 3V-level USB-to-TTL adapter and a serial terminal.
Yx 
