Fireye NX6100 F43: Gas pressure limit exceeded or sensor fault, what to check?
My Fireye NX6100 controller is showing an F43 fault. This happens during modulation, and the gas pressure reading seems to jump around. What should I check first?
The Fireye NX6100 F43 fault indicates that the controller's internal gas pressure sensor has detected a pressure outside the set operating limits or the sensor itself is not responding. This fault can occur at any point where gas pressure is supervised, from pilot ignition through modulation. It's important to distinguish this from external low or high gas pressure switch alarms, which typically appear as F01-F09, F12, or F13.
Likely causes and checks
1Sensor or CANbus fault
- Points to it
- The gas pressure sensor itself may be faulty, or there could be an issue with its CANbus wiring. This often manifests as erratic or missing pressure readings.
- Check
- Inspect the gas pressure sensor and its CANbus wiring for any damage or loose connections.
2Supply pressure low
- Points to it
- The gas supply pressure to the burner may be insufficient, especially during high fire demand or when other equipment starts drawing gas. This would cause the controller's sensor to read below the operating limits.
- Check
- Verify the gas supply pressure upstream of the burner regulator.
3Regulator lock-up or creep
- Points to it
- A faulty gas pressure regulator can either 'lock up' at a high pressure or 'creep' upwards, leading to an overpressure condition detected by the controller's sensor, particularly at light-off or after shutdown.
- Check
- Have the gas pressure regulator inspected for lock-up and creep issues.
Next check: Given the symptom of the reading jumping, the most likely cause is an issue with the gas pressure sensor or its CANbus wiring. Check the sensor and its CANbus wiring first.
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