Systematic fault isolation
DIY Nitrox analyser troubleshooting
Start with the observed state, change one thing at a time, and preserve the firmware version and exact error before resetting anything. A fault that disappears after reboot has not proved measurement accuracy.
Do not calibrate around a warning. Disconnect power for heat, swelling, damaged insulation, moisture, burning smell, or unexplained current draw. Re-establish calibration and independent verification after every measurement or power fault.
Sensor and ADS1115
Measurement faults
| Symptom | Likely checks | Safe next action |
|---|---|---|
| Sensor disconnected | Cell output below accepted range; loose connector; reversed or broken wire; ADS1115 power/I2C fault; exhausted cell. | Stop analysis. Inspect seating, A0/A1 polarity, 3.3 V, GND, GPIO17/18, ADDR-to-GND, moisture, and cell condition. |
| Sensor error or out of range | Invalid or excessive signal, accidental powered cell lead, wiring short, wrong ADC channel, or unsuitable cell. | Remove the sample and power. Check the schematic with a meter before reconnecting. Never power the galvanic cell. |
| Reading jumps or jitters | Long signal wires, poor joint, cable movement, electrical noise, unstable flow, moisture, or ageing cell. | Shorten/secure signal wiring, inspect joints and strain relief, stabilise flow and temperature, then recalibrate and verify. |
| Air not near reference after calibration | Contaminated air, pressure or temperature change, poor sampling, weak cell, or hardware drift. | Use clean air, stabilise, recalibrate once, and compare with trusted equipment. Remove from service if disagreement remains. |
| Slow response or no return to air | Restricted gas path, trapped sample, wet flow adapter, damaged membrane, or end-of-life cell. | Stop use, inspect the gas path and cell, dry/repair as appropriate, then run a complete known-gas response check. |
Local setup
Wi-Fi and Web UI faults
Cannot find the setup network
- Confirm the analyser is awake and the display has completed startup.
- Look for
NitroxAnalyser-XXXX; XXXX matches the device-ID suffix. - If saved Wi-Fi exists, check the WiFi information screen for its current address.
- Deleting the last saved profile returns the analyser to setup-AP mode.
- Power-cycle only after recording the current state and error.
192.168.4.1 will not open
- Stay connected when the phone reports “No Internet”.
- Enter
http://192.168.4.1/exactly—not HTTPS. - Temporarily disable VPN, private relay, and automatic mobile-data switching.
- Forget and rejoin the network with the password shown on the device; factory default is
12345678. - Try another browser close to the analyser.
Bluetooth and labels
Niimbot printer faults
| Symptom | Checks |
|---|---|
| No printers found | Charge and switch on the B1/B21, close the cover, end any phone-app connection, move it close, wait for boot, and scan again. |
| Configured printer will not connect | Power-cycle the printer, remove competing Bluetooth connections, confirm the saved device, and retry once from stable analyser power. |
| Double press does nothing | Use two short press-and-release gestures on the main analysis screen, with the second release within about 0.9 seconds. Confirm the sensor is valid and a printer is saved. |
| Partial, blank, or misaligned label | Discard it. Check gapped label stock, roll direction, cover latch, printer charge, range, and model. Reprint only after the live reading is stable. |
| Wrong name, date, or MOD | Correct the active name, clock/timezone, and print pO2 setting in the Web UI; then generate and verify a new label. |
Power, licence, and firmware
System faults
Power and sleep
- Default battery sleep occurs after five minutes below 27% O2; press the button to wake.
- Battery and USB sleep timers are separate; zero disables the selected timer.
- Check connector polarity, voltage, cable, and battery condition for resets or flicker.
- Stop immediately for heat, swelling, smell, or unstable power.
Licence and updates
- Copy the exact 12-character Device ID before requesting or entering a code.
- Licence codes are device-bound; email hello@nitroxanalyser.com for manual purchase support.
- Use update-only for routine firmware updates so settings and licence remain intact.
- Use full install only for a new board, recovery, unknown firmware, or partition change.
Support evidence
What to record before contacting us
- Firmware version and the 12-character Device ID.
- Exact display/Web UI message and whether the fault is repeatable.
- Diagnostics cell millivolts, jitter, battery voltage, and USB state.
- Photo of wiring or screen, printer model, label stock, and sequence of actions.
- What changed immediately before the problem. Never send Wi-Fi passwords or licence keys.