Alarm: Heater Error
Manufacturer: Yokogawa
Alarm Description
The Heater Error alarm indicates that the zirconia sensor heater is not operating within the required temperature range. Accurate oxygen measurement is not possible unless the heater is functioning correctly.
Typical Symptoms
- Oxygen reading frozen, zero, or invalid
- Analyzer remains in warm-up state
- Repeated heater alarms after power-up
- Sudden signal loss after temperature increase
Probable Causes (Most Common First)
- Heater element open circuit or burnout
- Heater power supply failure
- Loose or corroded heater wiring
- Excessive process or flue gas temperature
- Electronics module malfunction
Field Checks
- Verify analyzer power supply and fuses
- Check heater status indication on converter
- Measure heater resistance vs specifications
- Verify heater voltage at probe terminals
- Inspect wiring and connectors
- Confirm process temperature is within limits
Corrective Actions
- Replace heater assembly if resistance is abnormal
- Restore heater power supply
- Repair or replace damaged heater wiring
- Install heat shielding or relocate probe if required
- Replace electronics module if heater control fails
Impact on Measurement
When a heater error is active, oxygen measurement is unreliable and must not be used for combustion control or emissions reporting until the alarm is cleared.