Yokogawa OX400 — Alarm Codes (Quick Actions)
Practical first actions for common OX400 alarms. Use decision trees for systematic troubleshooting.
Tip: If O₂ is unstable, solve probe fouling / purge / calibration leaks first.
Calibration will not hold if the measurement is unstable.
Unstable / Fluctuating O₂
- Unstable Reading — check probe condition, purge air (if equipped), cal manifold leaks, grounding.
- Spikes — often cal valve leakage or process swings.
Calibration Alarms
- Calibration Failure — wrong gas, low flow, leaks, probe fouling, insufficient stabilization time.
- Span Not Achievable — check leaks first, then probe fouling.
Probe Fouling / Plugging
- Slow Response — filter/probe plugging, heavy dust zone, purge not working.
- Frequent Drift — fouling repeating due to insufficient purge or poor location.
Communication / Output Fault
- DCS Frozen / Bad Quality — check 4–20 mA wiring/scaling or Modbus/Ethernet mapping.
- Comms Alarm — check IP/serial settings, cable/switch, polling and registers.