GC8000 Error 603 – Oven Heater Failure
Oven temperature control failure during analyzer startup.
Case Snapshot
- Analyzer: Yokogawa GC8000
- Error Code: 603
- Application: Refinery – Process Unit GC
- Status: Analyzer not coming online
Observed Symptoms
- GC stuck in startup sequence
- Error 603 displayed after warm-up attempt
- Oven temperature remained at ambient
- No temperature rise even after restart
Initial Actions Taken
- Analyzer restarted multiple times
- Method reloaded from backup
- Controller reset performed
These actions did not clear the alarm because the failure was hardware-related.
Detailed Diagnosis
- Oven temperature trend monitored – no increase observed
- Heater supply voltage checked – present
- RTD resistance measured – normal (~110 Ω at ambient)
- Heater output current measured – zero
Root Cause Identified
The oven heater relay on the oven control board failed to switch, preventing heater power from reaching the oven element.
Corrective Action
- Oven control board isolated and removed
- Heater relay confirmed faulty
- Oven control board replaced
- Analyzer restarted and monitored
Result After Fix
- Error 603 cleared automatically
- Oven reached setpoint within normal warm-up time
- GC returned to stable analysis
Failure Logic (Simplified)
Lessons Learned
- Error 603 is typically a hardware failure
- Healthy RTD does not guarantee heater operation
- Heater current measurement is critical
- Repeated restarts do not fix heater circuit faults