Bell and Gossett E12

What does Bell and Gossett E12 mean?

E12 indicates the e-90E Smart Pump cannot read a valid signal from the external pressure sensor. In HCS, MSE, or MSY control modes the pump requires a 4–20 mA pressure feedback signal to regulate system pressure. When that signal is absent or outside range, the pump trips to prevent uncontrolled operation. E12 does not appear in ACT (actuator/speed) mode.

Symptoms

• Pump stops and displays E12 on the control panel.
• STATUS LED illuminates red steady.
• Fault only occurs when P25 (control mode) is set to HCS, MSE, or MSY — not ACT.
• Fault signal relay activates, alerting connected BMS.

Common causes

• Pressure sensor connection cable disconnected or broken.
• Pressure sensor failed or wired to wrong terminals.
• 4–20 mA sensor signal below 4 mA threshold (open circuit or sensor power loss).
• Incorrect sensor type or range connected to P1 terminals.

Diagnostic steps

1. 01

   Verify sensor is installed and powered

   Confirm a pressure sensor is physically connected to the P1+ and P1- terminals (pins 9–10 on single-phase; pins 18–17 on three-phase). The pump supplies +15 VDC sensor power on P1+.

2. 02

   Inspect sensor wiring continuity

   Check the connection cables for open circuits, reversed polarity, or damaged insulation. Measure continuity from the sensor to the terminal block. Re-terminate any suspect connections.

3. 03

   Measure sensor output signal

   With power on, measure the 4–20 mA signal at the P1 terminals using a calibrated meter. The signal should read between 4 mA (0 pressure / zero) and 20 mA (full scale). A reading below 4 mA indicates sensor failure or open circuit.

4. 04

   Verify P40 and P42 parameters

   Confirm parameter P40 is set to P1 for external pressure sensor operation. Verify P42 is set to the correct full-scale pressure matching the installed sensor (e.g., 0–10 bar or 0–145 PSI).

5. 05

   Replace sensor if signal is absent or out of range

   If the sensor outputs no signal or an incorrect signal after verifying wiring, replace the pressure sensor with a compatible 4–20 mA transducer rated for the system pressure range.

When to call a professional

Contact a licensed technician if E12 persists after replacing the sensor and verifying all wiring. Persistent pressure sensor faults in a correctly wired system may indicate a failed sensor input circuit on the drive PCB, requiring factory-level board diagnostics or replacement.