Vaillant ecoTEC Plus 428 runs a 5 V ratiometric transducer — the display board reads voltage directly.

None — the PCB self-references at 0 bar and 1.5 bar; recommission per OEM sheet.

Do I need to notify the manufacturer?

Only if the Vaillant ecoTEC Plus 428 is in warranty — Vaillant require log of any part swap for labour claims.

How to Replace the Pressure Sensor on a Vaillant ecoTEC Plus 428 (UK)

Fit a new pressure transducer on Vaillant ecoTEC Plus 428 when the display shows correct pressure at rest but locks out on heat-up.

The transducer on Vaillant ecoTEC Plus 428 threads or clips into the hydraulic block. Drop pressure to zero before removal.

Refit with a new O-ring; over-tightening cracks the plastic body.

Refill the Vaillant ecoTEC Plus 428 to 1.2 bar cold. Bleed high-point radiators and the internal AAV.

Run a full flue-gas analysis after 15 minutes. Log the reading against the OEM commissioning envelope in the Benchmark book.

Digital or analogue?: Vaillant ecoTEC Plus 428 runs a 5 V ratiometric transducer — the display board reads voltage directly.
Calibration?: None — the PCB self-references at 0 bar and 1.5 bar; recommission per OEM sheet.
Do I need to notify the manufacturer?: Only if the Vaillant ecoTEC Plus 428 is in warranty — Vaillant require log of any part swap for labour claims.

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