Carrier / Pressure / Flow

• Carrier Pressure Low/High — confirm supply, regulator stability, leaks, filter restriction
• Flow Controller Fault — check controller status, setpoints, valve response, sensor wiring
• Leak Suspected — soap test fittings, verify column/valve block connections, check vent lines

First action: verify pressure is stable (no hunting). Unstable pressure causes retention time shift + noisy baseline.

Oven / Temperature

• Oven Not Ready — heater output, temp sensor, control loop, fan/airflow (if present)
• Temperature Deviation — check setpoint vs actual, sensor drift, wiring, controller tuning

First action: confirm oven temperature is stable at setpoint before judging chromatogram quality.

Detector / Signal Quality

• Baseline Noise/Drift — carrier purity, leaks, detector contamination, grounding
• Detector Fault — electronics, sensor, power supplies, module seating
• Signal Out of Range — incorrect gain settings, detector issue, wiring problem

Method / Results

• Retention Time Shift — carrier flow change, column/oven temp drift, pressure instability
• Poor Repeatability — injection valve wear, sample pressure instability, contamination
• Missing Peaks — stream selection, valve timing, column degradation, sample issue

FID Specific (if installed)

• FID Flameout — fuel/air pressures, ignition, dirty jet, flow imbalance
• FID Ignition Fail — igniter issue, gas supply problem, wet/contaminated lines