The Eurotherm 2408 (and the 2408F profiling variant) remains one of the most widely installed 1/8-DIN PID temperature controllers in furnaces, environmental chambers, and process skids across Europe. When one throws an error mid-process, downtime is expensive. Below are the messages you are most likely to meet, what they actually mean, and which ones justify replacing the unit. Always cross-check against the official Eurotherm 2408 engineering handbook for your firmware version before acting.
Sensor and loop faults (most common in the field)
- S.br — Sensor break. The controller sees an open circuit on the process input. Check thermocouple continuity, terminal tightness, and compensating cable polarity before blaming the controller. A failed thermocouple is by far the most common cause of a 2408 “fault.”
- L.br — Loop break. The controller is driving the output but the process value is not responding within the expected time. Typical culprits: failed heater element, blown SSR or contactor, or a wiring fault downstream — not the controller itself.
- Ld.F / SSr.F / Htr.F — Load / SSR / heater circuit faults (on units fitted with current transformer monitoring). These indicate the measured load current does not match what the output state expects — a partial heater failure or a short-circuited SSR.
- HHHH / LLLL — Process value over/under range. The input is beyond the configured range: wrong sensor type selected, wrong linearisation, or a genuinely out-of-range process.
Internal and power-up errors
- EE.Er — EEPROM / configuration error. Stored configuration or calibration data failed its check. Sometimes recoverable by re-entering configuration mode and saving; recurring EE.Er indicates failing non-volatile memory — replace the unit.
- Err1…Err5 series — power-on self-test failures covering ROM, RAM, watchdog, keyboard, and internal configuration checks. A one-off event after a brown-out can be cleared by a power cycle; repeat occurrences mean the controller hardware is failing.
- Hw.Er — Hardware error. A fitted module does not match the configuration, or a module has failed. Check module seating first — boards do walk loose after years of thermal cycling in a hot panel.
Repair, replace, or upgrade?
The 2408 is long since out of production, superseded by the EPC3000 series. That leaves three realistic paths when a unit fails:
- Fix the periphery. The majority of “controller faults” are sensors, SSRs, and wiring. Prove the loop before spending anything on the controller.
- Drop-in replacement with a tested refurbished 2408. Same cutout, same wiring, same configuration — clone the config sheet across and you are running again in under an hour, with no revalidation of panel drawings. For regulated pharma environments where change control is costly, this is usually the cheapest path by a wide margin.
- Migrate to a current controller. Right when the panel is due a broader refit anyway — but budget for rewiring, reconfiguration, and documentation updates, not just the hardware price.
PLC North stocks tested Eurotherm 2408 and 2408F controllers with matching order codes on request — tell us your existing code (e.g. 2408/CC/VH/…) and we will match hardware options so it drops straight into your panel.