Which sequence of steps describes a solid troubleshooting flow for a transmitter that reads low but stays steady?

• A. Immediately replace transmitter; ignore loop diagnostics; call vendor.
• B. Check power supply and loop wiring; verify input conditions; perform calibration check; swap with known-good sensor and transmitter; inspect loop diagnostics; verify process variables; reassess.
• C. Disable power; hope for improvement; re-enable.
• D. Change process variable to normal; assume sensor ok.

Answer: (B)

A methodical, step-by-step troubleshooting flow is being tested here: when a transmitter reads low but remains steady, you should first confirm the basics—power supply within specification and secure loop wiring—because undervoltage or loose connections can depress the signal without indicating a transmitter fault. Next, verify input conditions to ensure the sensor is operating in its expected range and isn’t being driven into an abnormal mode; a calibration check helps confirm the transmitter’s scale hasn’t drifted and remains accurate. Swapping in a known-good sensor and a known-good transmitter is a powerful step to isolate where the fault lies: if the readings return to normal with the known-good pair, the issue was in the original sensor or transmitter; if not, the problem is likely in the loop or in process conditions. Inspecting loop diagnostics provides actionable information such as fault flags, current, and communication status, which helps pinpoint whether the problem is in the wiring, transmitter, or the process interface. Finally, verify the process variable against an independent measurement or reference to confirm whether the low reading reflects the actual process or is an instrument fault, and reassess from there to determine the appropriate corrective action.