S972 / M972 Endress+Hauser — Transmitter out of calibration (offset or span error)
At a glance
- Severity
- DEGRADED
- Domain
- INSTRUMENTATION
- Reference standard
- IEC 60770 / ISO 17025
- Product / context
- Calibration check required — Heartbeat Technology
What it means
The measurement transmitter provides a 4-20mA signal that does not correspond to the actual physical quantity. The error manifests as an offset (constant deviation across the entire range) or as a span error (increasing deviation toward full scale). The associated process control loop operates on an incorrect value, potentially causing product quality or safety issues.
Probable causes
- Sensor thermal drift after extended operation without recalibration.
- Change in installation conditions (e.g., static pressure, fluid density, mounting position) without recalibrating the transmitter.
- Transmitter zero not adjusted after installation (mechanical offset due to mounting position).
- Primary sensor partially degraded (e.g., deformed pressure diaphragm, aged thermocouple).
Where to start
Compare the transmitter reading with a reference standard (certified pressure gauge, reference thermometer, process calibrator). Is the deviation constant across the entire range (offset)?
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the five IndexOS apps: free, works offline.
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The same fault on other brands
More Endress+Hauser codes
- F041 — PT100/PT1000 probe faulty (open circuit or short circuit)
- F270 / F437 — 4-20mA signal out of range (below 3.8mA or above 20.5mA)
- HART Comm Error — HART communication impossible (no response from transmitter)
- S140 / S141 — Noisy analog signal (electromagnetic interference)